The front entrance of Sandy Hook Elementary School, where the gunman Adam Lanza entered.  NEWTOWN, Conn. â Adam Lanza spent the final months of his life mostly alone in his bedroom. His windows were covered with black trash bags. He was preoccupied with violent video games and created a spreadsheet of some of the worst massacres in American history.  Mr. Lanza refused to speak even to his mother, communicating with her only by email, even though their bedrooms shared the same floor of their house on Yogananda Street.  He would not eat unless his food was arranged in a particular way on his plate. He hated birthdays and holidays, and forbade his mother from putting up a Christmas tree.  He also made her get rid of a cat he did not like.  No one else was allowed into his room, including his mother, who nevertheless did her sonâs laundry daily because he changed his clothes often.  Among their few outings together were trips to the shooting range. She planned to buy him a gun for Christmas last year.  Mr. Lanza, 20, could not connect with people but obsessed over âDance Dance Revolution,â an interactive video game he played in the lobby of a nearby movie theater, spending as long as 10 hours at a time trying to follow dance routines as they flashed on the screen.  Last year, four days before her son killed 20 first graders and six adults at Sandy Hook Elementary School and then shot himself, Ms. Lanza cooked him some of his favorite meals and then left for a three-day trip to New Hampshire.  Ms. Lanza returned on Dec. 13 at 10 p.m.  The next morning, her son shot and killed her in her bed.  A 48-page report released on Monday by the stateâs attorney in Danbury, Stephen J. Sedensky III, offers a vivid and chilling portrait of the young man responsible for one of the nationâs worst mass shootings, and chronicles his rampage in the school.  But what it does not answer is why.  The long-awaited report does not suggest a motive for Mr. Lanzaâs actions, even as it offers a glimpse into his strange, troubled life. It comes nearly a year after the shooting set off a national discussion about gun control, mental health and violence in American popular culture.  In that time, families of the Sandy Hook Elementary victims have struggled to put their lives back together, the town has tried to heal and the school has been razed. But, until Monday, little information compiled by investigators had been publicly released.  Even basic facts, like the path Mr. Lanza took inside the school, were kept secret.  After the shooting, the Connecticut General Assembly passed bills to limit what could be made public. The state also fought to prevent the release of the recordings of the emergency calls to 911 from people inside the school. At a hearing on Monday before the reportâs release, Judge Eliot Prescott of New Britain Superior Court said that he would review the tapes and soon decide whether to release them.  The report was based on voluminous evidence and interviews conducted by the Connecticut State Police and the stateâs attorneyâs office, along with federal authorities. It marks the end of the investigation.  Investigators struggled to make sense of âcontradictoryâ descriptions of Mr. Lanza by those who knew him.  The report notes that while âsignificant mental health issuesâ affected his ability to live a normal life and interact with others, it remained unclear if they contributed in any way to his actions last December. Mr. Lanza received a diagnosis in 2005 of an autism variant known as Aspergerâs syndrome, but there is no evidence that people with Aspergerâs are more likely than others to commit violent crimes.  Mr. Lanza was treated by mental health professionals, according to the report, but none of them saw anything that predicted his future behavior.  âTutoring, desensitization and medication were recommended,â the report said. âThe shooter refused to take suggested medication and did not engage in suggested behavior therapies.â  There were reports of troubling behavior as early as the fifth grade, when Mr. Lanza produced âThe Big Book of Grannyâ for a class project. The main character had a gun in her cane and shot people.  In 2006, as a seventh grader, Mr. Lanza was described by a teacher as intelligent but obsessed with violent imagery.  Joseph Berger reported from Newtown, and Marc Santora from New York. Elizabeth Maker contributed reporting from Newtown, and Kristin Hussey from New Britain, Conn.  This article has been revised to reflect the following correction:  An earlier version of this article misstated the Connecticut city from which Kristin Hussey contributed reporting. It is New Britain, not Bridgeport.
Almost a year after Adam Lanza killed 26 children and adults in a Newtown, Conn., elementary school, an investigative report shed new light on his internal life and complicated relationship with his mother.