Report: Alleged Golden State Killer Joe DeAngelo Watched Men Rape His Sister

Alleged Golden State Killer Joe DeAngelo was left traumatized by witnessing a rape, according to his nephew.

It has emerged that DeAngelo, 72, who has been charged with 12 murders and suspected of raping 50 people, saw his young sister being raped.

DeAngelo, aged 9 or 10, reportedly saw his seven-year-old sister being raped by two men on an Air Force base in Germany.

His nephew Jessie Ryland said: "That is pretty crazy for a kid to see his sister being violated."

Ryland claims his mother told him about the incident before she passed away from cancer last year.

"Maybe that was the start of Joe going wacko," he added.

Lawyers defending DeAngelo could claim that the alleged killer became preoccupied with rape after his sister's sexual assault.

He has not yet entered a plea and is scheduled to return to court in Sacramento on Monday. It is not clear if his sister's sexual assault would factor into DeAngelo's criminal trial.