Transcript for New details emerge on alleged 'Golden State Killer'

We are back with disturing new details about the golden state killer from the police chief who fired him. ABC's whit Johnson has the story. Reporter: This morning, accused serial killer Joseph Deangelo expected back in court. This as californians now recall just how chillingly close they came to the man prosecutors say is responsible for at least a dozen murders and more than 50 rapes beginning in the midantidepressants 70s. His defense attorney attempting to block investigators from collecting more DNA, fingerprints and photographs from specific parts of his body. His former boss wondering if he could have helped catch him 30 years ago. Guilt, some embarrassment, you know, I just wish we -- it could have been stopped a long time ago. Reporter: Retired Auburn police chief willic fired him for stealing dog repellent and a hammer and he later filed a lawsuit against the department. A short time after he had been fired I woke up one morning, my 4-year-old daughter was laying alongside the bed. She said, dad, last night, there was someone looking in my bedroom window with a flashlight. Did you think that could have been gee outside your home? No, I did not. Reporter: What he didn't know at the time, that the man he fired would be arrested decades later for brutal crimes he's accused of committing while on the force. And now victims empowered by Deangelo's arrest are bravely telling their stories. The serial rapist is in your room and then what. The whole time he had been threatening me do you want to die. He warrants fear and I knew that so I just told him, I don't care. Reporter: Former chief willic tells me years ago Deangelo gave him a tour of his home explaining he and his wife slept in separate bedrooms. Willick now wondering whether that arrangement let him sneak out of his own house at night. We'll have much more on "20/20" in Friday 10:00, 9:00 central. Coming up, what would you do if you saw this, hundreds of

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