New insight into the mind of suspected serial killer Joseph DeAngelo emerged this week. First published by Buzzfeed News on Friday, it was suggested by members of DeAngelo's family that his crime spree was inspired by a rape that targeted his own sister. 35-year-old Jesse Ryland, one of DeAngelo's nephews, claimed that a nine or ten-year-old DeAngelo witnessed the rape of his sister Constance, who was then only seven years old.

According to the DeAngelo family, Constance was sexually assaulted at an unidentified Air Force base, in West Germany, in the 1950s.

Jesse claims that his mother, who passed away from cancer in 2017, only informed him of this assault while she was on her deathbed. "Maybe that was the start of Joe going wacko," Jesse reported his mother saying. "Joe" refers to Joseph DeAngelo, the man whom the FBI and California law enforcement say raped over fifty women and killed twelve between 1976 and 1986. DeAngelo was known as the "East Area Rapist," "The Golden State Killer," and "The Original Night Stalker."

Another theory now being pondered, about the source of DeAngelo's rage, concerns his failed engagement with a woman named Bonnie Colwell. The couple broke off their planned marriage in the early 1970s, and one of the East Area Rapist's victims told police that she heard her attacker saying to himself, "I hate you, Bonnie."

Pattern of behavior

It is common for sexual predators and serial killers to have some kind of psychological or physical trauma in their background.

Ann Wolbert Burgess, a professor of psychiatric nursing at Boston College, told Buzzfeed that serial killers often develop their violent fantasies at a very early age. Regarding the story of his sister's sexual assault, Burgess said: "What probably happened was that it was something that he [DeAngelo] kept on his mind."

California investigators and the prosecution team tasked with convicting DeAngelo have so far refused to comment on this possible motivation.

Despite this, Ryland has provided further evidence that DeAngelo may have been inspired by a loveless childhood. According to this relative, DeAngelo and his siblings were physically abused by their father. In turn, Kathleen DeAngelo, the abused mother, reportedly attacked her daughter Constance.

Joseph DeAngelo, Sr. served in the US Air Force, and his family did live in West Germany for a time.

Ryland says that the elder DeAngelo was known as an abusive spouse on base, and he was once threatened with a discharge in Germany if he continued to assault his family.

More out there?

The last known crime of the Golden State Killer occurred in 1986. In the Southern California city of Irvine, 18-year-old Janelle Cruz was found bludgeoned to death by a realtor. After the Cruz murder, the GSK did not carry out another known attack. Police investigating the case have now told the media that it is possible that DeAngelo continued to carry out rapes and other violent crimes between 1986 and 2018.