I have a test where I am given the following article, what is an answer for the question: What is the full name of the person who left an estate to their granddaughter? ?

Texas Rangers Gene Autry and Frog Millhouse are traveling undercover as western troubadours in search of the killer of old, half-blind Frank Martin. Their only clues are a guitar string (the murder weapon) and Martin's horse Swayback that hold the key to finding the dead man's lost goldmine.
Following Frank Martin's funeral, Martin's granddaughter, Joan, meets her uncle, John Martin, and Lon Dillon, who flirts with her. Lawyer Henry Nolan reads Martin's will, revealing that the deceased left John $5,000 and the remainder of the estate to Joan. John tells Joan that he suspects Gene of her grandfather's murder and persuades her to hold a masquerade dance to lure Gene into town.
Meanwhile, Gene learns that Martin was nearly blind and relied on his horse Swayback to guide him. By following Swayback, whom Lon, John, and Henry have all tried to buy, Gene discovers that Martin had indeed located a gold mine. Gene and Frog escape a trap set for them at the dance and save Joan when she is nearly strangled by another guitar string. Then Gene discovers that John's guitar is missing a string.
John and Pablo, who have uncovered Swayback's hiding place, find the mine and are followed by Henry, Lon, and Hank Polk. As they argue among themselves, Gene surprises them and reveals that he is a Texas Ranger assigned to the Martin murder case. By claiming that Frog is a fingerprint expert, Gene tricks Henry into admitting his guilt. Henry is then arrested by the sheriff, who is waiting in the mine according to Gene's instructions. Finally, Joan learns that Gene has recorded the deed to the mine in her name.

Frank Martin