(Caution graphic content) Trayvon Martin case: 911 call: Yelling & gunshot heard in background  FILE - In a Tuesday, July 2, 2013 file pool photo, prosecutor Bernie de la Rionda, right, demonstrates a possible scenario while questioning state's witness Sanford Police officer Chris Serino, during the George Zimmerman trial in Seminole circuit court, in Sanford, Fla. Called as a prosecution witness, Serino testified he found Zimmerman credible in his description of his fight with Martin. But the judge ordered jurors to ignore his opinion, granting a prosecution request to toss the statement because it is improper for one witness to testify about the credibility of another witness. Photo: AP  FILE - In a Tuesday, July 2, 2013 file pool photo, prosecutor...  George Zimmerman, left, speaks to defense counsel Don West during a recess in his trial in Seminole circuit court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman, left, speaks to defense counsel Don West during...  FILE - In a Friday, July 5, 2013 file pool photo, Volusia and Seminole County associate medical examiner Shiping Bao MD testifies during George Zimmerman's trial in Seminole circuit court, in Sanford, Fla. Bao told jurors Friday that Martin was alive from one to 10 minutes after he was shot in the heart by Zimmerman. Later, he conceded that his testimony was different from a deposition he gave last year in which he said the Miami teen lived from one to three minutes after the gunshot. During a prickly cross-examination, Bao said it was possible Martin may have been able to move after being shot. That is important because Martin’s arms are positioned differently in a photo than the way Zimmerman described them being after he fired the shot. Photo: Orlando Sentinel, Gary W. Green, Pool  FILE - In a Friday, July 5, 2013 file pool photo, Volusia and...  Sanford police officer Chris Serino testifies during the George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Sanford police officer Chris Serino testifies during the George...  FILE - In a Friday, July 5, 2013, file pool photo, Trayvon Martin's mother, Sybrina Fulton, takes the stand during George Zimmerman's trial in Seminole County circuit court, in Sanford, Fla. Zimmerman's mother and Martin's mother each testified Friday that it was her son, not the other woman's, who can be heard screaming for help on a 911 call. Identifying the voice could be critical to the case because it could help the jury determine who the aggressor was during the scuffle. Photo: Orlando Sentinel, Gary W. Green, Pool  FILE - In a Friday, July 5, 2013, file pool photo, Trayvon Martin's...  The parents of Trayvon Martin, Tracy Martin, right, and Sybrina Fulton, listen to the testimony of Sanford police officer Chris Serino during the George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  The parents of Trayvon Martin, Tracy Martin, right, and Sybrina...  FILE - In a Tuesday, July 2, 2013 file pool photo, Judge Debra Nelson instructs the jury at the George Zimmerman trial in Seminole circuit court, in Sanford, Fla. After presenting more than three dozen witnesses over two weeks, prosecutors rested their case on Friday.As is typical after the prosecution rests, the defense asked Judge Nelson to acquit Zimmerman, claiming prosecutors’ didn’t prove their case. The judge denied the request. Photo: Orlando Sentinel, Joe Burbank, Pool  FILE - In a Tuesday, July 2, 2013 file pool photo, Judge Debra...  George Zimmerman, right, is greeted by defense counsel Don West at the start of his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman, right, is greeted by defense counsel Don West at...  FILE - Friday, July 5, 2013 file pool photo, George Zimmerman's mother Gladys Zimmerman takes the stand during George Zimmerman's trial in Seminole County circuit court, Friday, July 5, 2013, in Sanford, Fla. Zimmerman's mother and Trayvon Martin's mother each testified Friday that it was her son, not the other woman's, who can be heard screaming for help on a 911 call. Photo: Orlando Sentinel, Gary W. Green, Pool  FILE - Friday, July 5, 2013 file pool photo, George Zimmerman's...  Mark Osterman, a friend of George Zimmerman, describes the type of gun Zimmerman owned while testifying during Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Mark Osterman, a friend of George Zimmerman, describes the type of...  Trayvon Martin's brother Jahvaris Fulton takes the stand during George Zimmerman's trial in Seminole County circuit court, Friday, July 5, 2013, in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Gary W. Green, Pool  Trayvon Martin's brother Jahvaris Fulton takes the stand during...  LeAnne Benjamin, a friend of George Zimmerman, smiles while identifying him in court during testimony in his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  LeAnne Benjamin, a friend of George Zimmerman, smiles while...  George Zimmerman, right, stands next to one of his defense attorneys, Don West, during his trial in Seminole circuit court, Friday, July 5, 2013, in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Gary W. Green, Pool  George Zimmerman, right, stands next to one of his defense...  The parents of Trayvon Martin, Tracy Martin and Sybrina Fulton, left, speak to State Attorney Angela Corey during the George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  The parents of Trayvon Martin, Tracy Martin and Sybrina Fulton,...  Assistant state attorney Bernie de la Rionda, right, talks to Sybrina Fulton, Trayvon Martin's mother, on the stand during a recess in George Zimmerman's trial in Seminole circuit court, Friday, July 5, 2013 in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Gary W. Green, Pool  Assistant state attorney Bernie de la Rionda, right, talks to...  George Zimmerman stands before the start of his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman stands before the start of his trial in Seminole...  Defense attorneys Mark O'Mara, left, Don West, center, stand with George Zimmerman during Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the 2012 fatal shooting of slain teen Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  Defense attorneys Mark O'Mara, left, Don West, center, stand with...  The parents of Trayvon Martin, Tracy Martin, left, and Sybrina Fulton, arrive for George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  The parents of Trayvon Martin, Tracy Martin, left, and Sybrina...  Amy Siewert, a firearms expert with the Florida Department of Law Enforcement, faces the jury as she demonstrates George Zimmerman's gun during his trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Amy Siewert, a firearms expert with the Florida Department of Law...  George Zimmerman arrives for his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman arrives for his trial in Seminole Circuit Court,...  Florida Department of Law Enforcement Crime Lab Analyst Anthony Gorgone, right, points to a jacket worn by George Zimmerman on the night Zimmerman shot Trayvon Martin during Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Behind Gorgone is Assistant District Attorney John Guy. Photo: Orlando Sentinel, Jacob Langston, Pool  Florida Department of Law Enforcement Crime Lab Analyst Anthony...  Sondra Osterman, a friend of George Zimmerman, listens to the 911 tape while while on the witness stand at Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Sondra Osterman, a friend of George Zimmerman, listens to the 911...  Florida Department of Law Enforcement Crime Lab Analyst Anthony Gorgone points at Trayvon Martin's sweatshirt during the George Zimmerman trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Florida Department of Law Enforcement Crime Lab Analyst Anthony...  Assistant state attorneys John Guy, left, and Bernie de la Rionda, right, display the hooded sweatshirt worn by Trayvon Martin the night he was shot by George Zimmerman during Zimmerman's trial in Seminole County circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Assistant state attorneys John Guy, left, and Bernie de la Rionda,...  George Zimmerman looks at State Attorney Angela Corey during a recess in his trial at the Seminole County circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman looks at State Attorney Angela Corey during a...  Defense attorney Mark O'Mara, left, and George Zimmerman smile at a witnesses answer during Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Defense attorney Mark O'Mara, left, and George Zimmerman smile at a...  Defense attorney Mark O'Mara, right, talks with Assistant state attorney John Guy before a recess during the George Zimmerman trial in Seminole circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Defense attorney Mark O'Mara, right, talks with Assistant state...  Defense attorney Mark O'Mara addresses judge Debra Nelson during the trial of George Zimmerman in Seminole County circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Defense attorney Mark O'Mara addresses judge Debra Nelson during...  Trayvon Martin's parents, Sybrina Fulton, left, and Tracy Martin, are seated at the start of George Zimmerman's trial in Seminole County circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of their son in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  Trayvon Martin's parents, Sybrina Fulton, left, and Tracy Martin,...  George Zimmerman enters the courtroom at his trial in Seminole County circuit court, in Sanford, Fla., Wednesday, July 3, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman enters the courtroom at his trial in Seminole...  Prosecutor Bernie de la Rionda, left, and defense attorney Mark O'Mara cross paths during the George Zimmerman trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Prosecutor Bernie de la Rionda, left, and defense attorney Mark...  George Zimmerman, right, talks with his attornies Mark O'Mara, left, and Don West, center, during a recess on the 17th day of Zimmerman's trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman, right, talks with his attornies Mark O'Mara,...  Defense attorney Mark O'Mara displays photos of George Zimmerman, taken the night of the shooting of Trayvon Martin, during cross examination of Jacksonville medical examiner Valerie Rao during Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Tuesday, July 2, 2013. Zimmerman is charged with second-degree murder in the shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Defense attorney Mark O'Mara displays photos of George Zimmerman,...  Jacksonville medical examiner Valerie Rao looks at photos as she testifies for the state in the trial of George Zimmerman in Seminole circuit court, in Sanford, Fla., Tuesday, July 2, 2013. Zimmerman is charged with second-degree murder in the shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Jacksonville medical examiner Valerie Rao looks at photos as she...  Prosecutor Bernie de la Rionda questions Sanford, Fla., police officer Chris Serino during the George Zimmerman trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Prosecutor Bernie de la Rionda questions Sanford, Fla., police...  Defense attorney Mark O'Mara questions Sanford, Fla., police officer Chris Serino during the George Zimmerman trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Defense attorney Mark O'Mara questions Sanford, Fla., police...  George Zimmerman arrives for the 17th day of his trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford, Fla. Zimmerman is charged with 2nd-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman arrives for the 17th day of his trial in Seminole...  The parents of Trayvon Martin, Sybrina Fulton, center, and Tracy Martin, right, stand with Trayvon Martin's Aunt, Stephanie Fulton Sands, left, as they wait for the jury's arrival in the courtroom at the start of the George Zimmerman trial on the 17th day, in Seminole circuit court, Tuesday, July 2, 2013 in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  The parents of Trayvon Martin, Sybrina Fulton, center, and Tracy...  Defense attorney Mark O'Mara, right, questions Sanford, Fla., police officer Chris Serino during the George Zimmerman trial in Seminole circuit court, Tuesday, July 2, 2013 in Sanford. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Defense attorney Mark O'Mara, right, questions Sanford, Fla.,...  A reenactment video shows George Zimmerman with Sanford police investigators, taken the after the Trayvon Martin shooting, is projected for the jury during the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  A reenactment video shows George Zimmerman with Sanford police...  Sanford, Fla., police officer Chris Serino identifies George Zimmerman in the courtroom during the 16th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Sanford, Fla., police officer Chris Serino identifies George...  A photo of George Zimmerman taken at the Sanford police station on the night of the Trayvon Martin shooting is projected on a video monitor for the jury during the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  A photo of George Zimmerman taken at the Sanford police station on...  George Zimmerman leaves court at the end of the session of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman leaves court at the end of the session of his...  State witness Dr. Hirotaka Nakasone, a senior voice recognition scientist with the FBI, testifies in the George Zimmerman trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  State witness Dr. Hirotaka Nakasone, a senior voice recognition...  The parents of Trayvon Martin, Tracy Martin, left, and Sybrina Fulton, arrive for the 16th day of the George Zimmerman trial, with their attorney, Daryl Parks, right, in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  The parents of Trayvon Martin, Tracy Martin, left, and Sybrina...  George Zimmerman, right, and defense attorney Don West, left, arrive for the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, right, and defense attorney Don West, left,...  George Zimmerman listens to state witness Dr. Hirotaka Nakasone, a senior voice recognition scientist with the FBI, during the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman listens to state witness Dr. Hirotaka Nakasone, a...  Sanford police officer Doris Singleton holds up a copy of George Zimmerman's written statement from the night of the shooting, while testifying in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Sanford police officer Doris Singleton holds up a copy of George...  George Zimmerman, right, with his attorneys, Mark O'Mara, left, and Don West, center, watch as an evidence video is projected on a screen during the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, right, with his attorneys, Mark O'Mara, left, and...  George Zimmerman, speaks with court personnel during a recess on the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, speaks with court personnel during a recess on...  George Zimmerman, left, is escorted by court personnel during a recess on the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, left, is escorted by court personnel during a...  Portions of George Zimmerman's written statement to Sanford police on the night of the shooting death of Trayvon Martin is projected on a video screen for the jury during the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  Portions of George Zimmerman's written statement to Sanford police...  George Zimmerman, right, stands up at the defense table with his attorneys, Mark O'Mara, left, and Don West, center, as he is identified by state witness Doris Singleton, a Sanford police officer, during her testimony in Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, right, stands up at the defense table with his...  George Zimmerman arrives for the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman arrives for the 16th day of his trial in Seminole...  George Zimmerman arrives for the 16th day of his trial in Seminole circuit court, in Sanford, Fla., Monday, July 1, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman arrives for the 16th day of his trial in Seminole...  FILE - This June 28, 2013 file photo, George Zimmerman's attorney, Mark O'Mara, right, cross examines witness Jonathan Good, during the 15th day of the Zimmerman trial in Seminole circuit court, in Sanford, Fla., Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  FILE - This June 28, 2013 file photo, George Zimmerman's attorney,...  FILE - This June 24, 2013 file photo, Tracy Martin, left, and Sybrina Fulton, center, parents of slain teen Trayvon Martin, speak in a news conference prior to opening arguments in the trial of George Zimmerman at the Seminole County Courthouse in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: John Raoux  FILE - This June 24, 2013 file photo, Tracy Martin, left, and...  FILE - This June 24, 2013 file photo, Don West, a defense attorney for George Zimmerman, displays a photo of his client from the night of the shooting of Trayvon Martin, to the jury during opening statements in Zimmerman's trial, in Seminole circuit court, in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  FILE - This June 24, 2013 file photo, Don West, a defense attorney...  FILE - This June 24, 2013 file photo, Assistant State Attorney John Guy gestures during his opening statement in George Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  FILE - This June 24, 2013 file photo, Assistant State Attorney John...  FILE - This June 26, 2013 file photo, witness Rachel Jeantel listens as defense attorney Don West questions her during her testimony at George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  FILE - This June 26, 2013 file photo, witness Rachel Jeantel...  George Zimmerman, right, is greeted by his attorney, Mark O'Mara, before the start of the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, right, is greeted by his attorney, Mark O'Mara,...  Witness Jonathan Good, right, watches prosecutor Bernie de la Rionda demonstrate the possible fight positions of George Zimmerman and Trayvon Martin, during the 15th day of the Zimmerman trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Witness Jonathan Good, right, watches prosecutor Bernie de la...  George Zimmerman waits for the jury to come into the courtroom during the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman waits for the jury to come into the courtroom...  George Zimmerman, left, sits with his defense lawyers, Don West, center, and Mark O'Mara, during the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, left, sits with his defense lawyers, Don West,...  George Zimmerman waits for his counsel before the start of the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman waits for his counsel before the start of the 15th...  George Zimmerman leaves the courtroom on a recess during the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman leaves the courtroom on a recess during the 15th...  George Zimmerman talks to court personnel during the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman talks to court personnel during the 15th day of...  Sanford police officer Timothy Smith holds up the gun that was used to kill Trayvon Martin, while testifying in the 15th day of the George Zimmerman trial, in Seminole circuit court in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Sanford police officer Timothy Smith holds up the gun that was used...  State evidence photos, including various photos of George Zimmerman on the night of the Trayvon Martin shooting, are projected on a video screen in the courtroom during the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  State evidence photos, including various photos of George Zimmerman...  State evidence photos, including this scene of George Zimmerman arriving at the Sanford Police station on the night of the Trayvon Martin shooting, are projected on a video screen in the courtroom during the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  State evidence photos, including this scene of George Zimmerman...  Attorney Mark O'Mara, defense counsel for George Zimmerman, holds an evidence photo of Trayvon Martin while questioning a state witness, on the 15th day of Zimmerman trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Attorney Mark O'Mara, defense counsel for George Zimmerman, holds...  Mark O'Mara, George Zimmerman's attorney, displays a photo of Zimmerman taken the night of the shooting of Trayvon Martin, to Zimmerman's physician, Lindzee Folgate, during her testimony on the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Mark O'Mara, George Zimmerman's attorney, displays a photo of...  State evidence photos, including a photo of George Zimmerman on the night of the Trayvon Martin shooting, are projected on a video screen in the courtroom during the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  State evidence photos, including a photo of George Zimmerman on the...  Sanford police officer Ricardo Ayala describes the fatal chest wound that he observed on Trayvon Martin, during the 15th day of the George Zimmerman trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Sanford police officer Ricardo Ayala describes the fatal chest...  State evidence photos, including this scene of George Zimmerman arriving at the Sanford Police station on the night of the Trayvon Martin shooting, are projected on a video screen in the courtroom during the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  State evidence photos, including this scene of George Zimmerman...  State exhibit photos, including this of George Zimmerman on the night of the Trayvon Martin shooting, are projected on a video screen in court during the 15th day of Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  State exhibit photos, including this of George Zimmerman on the...  George Zimmerman, left, smiles while standing next to defense counsel Lorna Truettwhile, waiting for the jury to leave the courtroom during the 15th day of his trial in Seminole circuit court, in Sanford, Fla., Friday, June 28, 2013. Zimmerman is charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman, left, smiles while standing next to defense...  George Zimmerman, center, talks to his defense team during his trial in Seminole circuit court in Sanford, Fla. Thursday, June 27, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman, center, talks to his defense team during his...  Witness Rachel Jeantel, right, continues her testimony to defense attorney Don West on day 14 of George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Thursday, June 27, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Witness Rachel Jeantel, right, continues her testimony to defense...  George Zimmerman, right, speaks with defense attorney Mark O'Mara during his trial in Seminole circuit court in Sanford, Fla. Thursday, June 27, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman, right, speaks with defense attorney Mark O'Mara...  Witness Rachel Jeantel continues her testimony during George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Thursday, June 27, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Witness Rachel Jeantel continues her testimony during George...  Rachel Jeantel, the witness that was on the phone with Trayvon Martin just before he died, gives her testimony during George Zimmerman's trial in Seminole circuit court in Sanford, Fla., Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Rachel Jeantel, the witness that was on the phone with Trayvon...  George Zimmerman glances back at the courtroom during his trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman glances back at the courtroom during his trial in...  Witness Jane Surdyka, left, points to a map of The Retreat at Twin Lakes being held by Assistant state attorney Bernie de la Rionda during George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  Witness Jane Surdyka, left, points to a map of The Retreat at Twin...  Witness Jane Surdyka gives her testimony during George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Witness Jane Surdyka gives her testimony during George Zimmerman's...  Defense attorney Mark O'Mara questions witness Jeannee Nanalo during George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Defense attorney Mark O'Mara questions witness Jeannee Nanalo...  Witness Jeannee Nanalo gives her testimony during George Zimmerman's trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Witness Jeannee Nanalo gives her testimony during George...  George Zimmerman, right, talks to attorney Don West during his trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Jacob Langston, Pool  George Zimmerman, right, talks to attorney Don West during his...  Defense attorneys, from left, Mark O'Mara, Don West and Lorna Truett, far right, stand with their client George Zimmerman, second from right, during Zimmerman's trial in Seminole circuit court in Sanford, Fla. Wednesday, June 26, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Defense attorneys, from left, Mark O'Mara, Don West and Lorna...  Diana Smith, crime scene technician for the Sanford Police Department, shows the jury George Zimmerman's gun, which was collected as evidence at the crime scene, during Zimmerman's trial in Seminole circuit court in Sanford, Fla. Tuesday, June 25, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  Diana Smith, crime scene technician for the Sanford Police...  The father of Trayvon Martin, Tracy Martin, cries as he listens to the description of his son's death during opening statements in the George Zimmerman trial, with Sybrina Fulton, Trayvon's mother, left, and Daryl Parks, a family attorney, right, in Seminole circuit court, in Sanford, Fla., Monday, June 24, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank/Pool  The father of Trayvon Martin, Tracy Martin, cries as he listens to...  Don West, a defense attorney for George Zimmerman describes the shooting of Trayvon Martin to the jury while holding an evidence photo of a gun during opening statements in Zimmerman's trial in Seminole circuit court, in Sanford, Fla., Monday, June 24, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Joe Burbank,Pool  Don West, a defense attorney for George Zimmerman describes the...  FILE - This June 20, 2013 file photo, George Zimmerman listens as his defense counsel Mark O'Mara questions potential jurors during Zimmerman's trial in Seminole circuit court in Sanford, Fla. Judge Debra Nelson said Saturday, June 22, 2013, that prosecution audio experts who point to Trayvon Martin as screaming on a 911 call moments before he was killed won't be allowed to testify at trial. Opening statement begin Monday June 24, 2013. Photo: Orlando Sentinel, Gary Green, Pool  FILE - This June 20, 2013 file photo, George Zimmerman listens as...  Judge Debra Nelson addresses concerns from the state and defense that need to be settled before opening arguments in George Zimmerman's trial in Seminole circuit court in Sanford, Fla., Friday, June 21, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: Orlando Sentinel, Gary W. Green, Pool  Judge Debra Nelson addresses concerns from the state and defense...  George Zimmerman, right, talks to jury consultant Robert Hirschhorn during the final stages of jury selection for his trial in Seminole circuit court in Sanford, Fla., Thursday, June 20, 2013. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. Photo: AP  George Zimmerman, right, talks to jury consultant Robert Hirschhorn...  From left, Rev. Jesse Jackson, Rev. Al Sharpton, and Benjamin Jealous, President of the NAACP lead the march for slain Florida teenager Trayvon Martin on Saturday, March 31, 2012 in Sanford, Fla. Protesters carried signs, chanted “Justice for Trayvon,” and clutched the hands of their children while they walked from Crooms Academy of Information Technology, the county’s first high school for black students, to the Sanford Police Department. The march was organized by the NAACP and was one of several taking place over the weekend. Martin was shot to death by 28-year-old George Zimmerman on Feb. 26 as he walked from back from a convenience store to his father’s fiancée’s home in a gated community outside Orlando. Photo: Julie Fletcher  From left, Rev. Jesse Jackson, Rev. Al Sharpton, and Benjamin...  In this Wednesday, March 28, 2012 photo provided by the New York City Council, council members gather on the steps of New York's City Hall under a photo of Trayvon Martin, the unarmed teenager who was shot by George Zimmerman, a neighborhood watch volunteer in Sanford, Fla. (AP Photo/New York City Council, William Alatriste) Photo: William Alatriste, HOPD  In this Wednesday, March 28, 2012 photo provided by the New York...  Trayvon Martin, 17, was shot to death Feb. 26. His killing prompted protests in his home state of Florida, where his killer is currently facing charges, and elsewhere. (Roberto Gonzalez / Getty Images)  Trayvon Martin, 17, was shot to death Feb. 26. His killing prompted...  FILE - This undated file family photo shows Trayvon Martin, a Florida teen who was shot and killed by neighborhood watch volunteer George Zimmerman in February. A judge on Friday, June 1, 2012 revoked Zimmerman's bond and ordered him returned to jail within 48 hours. Circuit Judge Kenneth Lester said Zimmerman misled the court about how much money he had available when his bond was set for $150,000 in April. Prosecutors claim he had $135,000 available that had been raised by a website he set up (AP Photo/Martin Family, File) Photo: Anonymous, Associated Press  FILE - This undated file family photo shows Trayvon Martin, a...  George Zimmerman sits in the courtroom during his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: AP  George Zimmerman sits in the courtroom during his trial in Seminole...  George Zimmerman stands before the start of his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman stands before the start of his trial in Seminole...  Sondra Osterman, a friend of George Zimmerman, listens to the 911 tape while while on the witness stand at Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Sondra Osterman, a friend of George Zimmerman, listens to the 911...  Adam Pollock, right, a central Florida gym owner and trainer, addresses the jury during a demonstration with defense attorney Mark O'Mara, left, during the George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Adam Pollock, right, a central Florida gym owner and trainer,...  Tracy Martin, the father of Trayvon Martin, pauses while testifying in George Zimmerman's trial at the Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of his son, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Tracy Martin, the father of Trayvon Martin, pauses while testifying...  Former Sanford police chief Billy Ray Lee, Jr., testifies in the George Zimmerman trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  Former Sanford police chief Billy Ray Lee, Jr., testifies in the...  Darwin Groves, left, and Donald Sampson, pose next to a sign that calls for George Zimmerman's innocence, Monday, July 8, 2013, outside of their business in Flint, Mich. George Zimmerman is currently being tried in the 2012 murder case of 17-year-old Trayvon Martin in Sanford, Fla. LOCAL TV OUT; LOCAL INTERNET OUT Photo: The Flint Journal, Jake May  Darwin Groves, left, and Donald Sampson, pose next to a sign that...  George Zimmerman sits at the defense table at his trial in Seminole Circuit Court, in Sanford, Fla., Monday, July 8, 2013. Zimmerman is charged with second-degree murder in the fatal shooting of Trayvon Martin, an unarmed teen, in 2012. Photo: Orlando Sentinel, Joe Burbank, Pool  George Zimmerman sits at the defense table at his trial in Seminole...
(AP) &acirc;�� Trayvon Martin's father testified Monday that he never denied it was his son's voice screaming for help on a 911 call, contradicting police officers' earlier testimony at George Zimmerman's second-degree murder trial.  Tracy Martin was the latest in a series of witnesses called by lawyers on both sides as they seek to convince jurors of who was the aggressor in the nighttime confrontation that left Trayvon Martin, an unarmed black teenager, dead in February 2012.  Later in the day, the Florida judge ruled that defense attorneys may present evidence to the jury that Trayvon Martin had marijuana in his system when he died.  Before Tracy Martin took the witness stand, the lead Sanford, Fla. police investigator who probed Martin's death testified that the father had answered &quot;no&quot; when the detective asked if the screams belonged to Trayvon Martin.  The judge denied a prosecution request to keep out parts of a toxicology report that shows Trayvon Martin had small amounts of marijuana in his system.  Next, the judge considered a prosecution motion to stop defense attorneys from presenting an animated depiction of the fatal fight between Martin and Zimmerman.  Prosecutors had requested that the animation commissioned by the defense not be mentioned or played at Zimmerman's trial, claiming it would only confuse jurors.  Zimmerman, a former neighborhood watch volunteer, has pleaded not guilty to second-degree murder and says he shot Martin in self-defense during an altercation in the gated townhome complex in Sanford where he lived.  Defense attorneys also called the owner of a gym where Zimmerman had gone to lose weight to explain to jurors the mixed-martial arts fighting method called &quot;ground and pound.&quot;