FRESNO, Calif. -- He is the alleged serial killer who spent nearly four decades on the run, but now that 72-year-old Joseph James Deangelo is in custody, questions from investigators about his role as the Visalia Ransacker and Golden State Killer pour in.
TIMELINE: A look back at the Golden State Killer's crime spree that lasted a decade
Dr. Eric Hickey is a well-known forensic psychologist and studies serial killers.
He says one of the elements in this case that stands out is the people DeAngelo is accused of targeting.
VIDEO: CoCo County Investigator Paul Holes is '100 percent sure' they have 'Golden State Killer'
"Most would just kill women or just kill men," Hickey said. "Seldom do you see them kill them together and then have sex with one of the victims."
That makes Hickey want to examine DeAngelo's past to see what his childhood was like. The criminal expert said, "He obviously had a lot of anger towards women he hated women he was very sadistic towards them."
VIDEO: Visalia detective came face to face with serial killer in 1975
The anger Hickey mentioned was echoed by one of DeAngelo's neighbors, Grant Gorman, who described an argument the two had over his dog.
"He called and said if you don't shut that dog up, I'll deliver a load of death," Gorman said.
Hickey also anticipates that once investigators go through DeAngelo's computer, they will likely find sadistic porn.
Click here for more stories, photos, and video on the Golden State Killer.