Kitty Genovese’s name became a symbol of New York City’s tragic indifference when a now questionable account of her 1964 murder outside her Queens apartment building focused on her neighbors ignoring her cries for help.

In a new documentary, “The Witness,” Kitty Genovese’s brother, Bill Genovese, turns investigator as he unravels the often false, but nonetheless potent, account of his sister’s case as it first appeared in the New York Times two weeks after the incident and, later, in Times editor A.M. Rosenthal’s 1973 book “38 Witnesses.”

Since 2004, Mr. Genovese has been on a mission to reclaim his favorite sibling’s humanity from the myth that engulfed her. For Mr. Genovese, his sister was the one person in the world who really understood him, who indulged his curiosities, who took him for rides in her red Fiat convertible.

“I’ve always been a questioner,” said Mr. Genovese, who is 68 years old and a retired administrator in Washington, Conn. “I can’t remember when I wasn’t.”

In 2004, the Times published a report addressing inaccuracies in its initial reportage. In the documentary, Mr. Genovese goes much further.