Transcript for New evidence could link alleged 'Golden State Killer' to crimes
We'll begin with new developments in the golden state killer case. New DNA tests and photos could link Joseph Deangelo to a spree of crimes across California and whit Johnson is tracking it and his lawyers tried to stop these tests from taking place. Reporter: That's right. Prosecutors requested that additional evidence in an effort to connect Joseph Deangelo to as many of the murders as possible. One of the original investigators told me why that information including specific photographs of his body is so critical to the case. Inside this Sacramento courthouse, a judge ruling that prosecutors may collect additional DNA, fingerprints and photos from Joseph Deangelo, evidence they say could further connect him to the laundry list of murders and rapes he's accused of. Prosecutors especially interested in knowing if Deangelo shares the same physical abnormality described by some of his alleged victims, a lead Carol Daly explored. If he's so underendowed we went to a specialist, a doctor to see if he had any patients that came in and -- You actually went to a doctor. Yeah. To see if the size of his anatomy was unique or rare. Yes, yes. I told you there was not a stone left unturned that we did in trying to identify this rapist and we didn't have any luck there. Reporter: Despite the clue, the serial killer would elude authorities for decades striking again and again. Then taunting some of his victims with chilling phone calls. Gonna kill you. Gonna kill you. Reporter: This morning, we're learning more about the man suspected of 12 murders and more than 50 rapes, retired Auburn police chief Nick Willick fired him. He would get close to your face and always be touching you. Always touchy. Yes, he was and, you know, I remember one time I told him, because I said, you know, Joe, my mother doesn't touch me as much as you do. Reporter: Jennifer Carol's father, Lyman Smith and stepmother Charlene were murdered. The same DNA found at that crime scene, investigators say would ultimately lead to Deangelo. Decades of living in fear now replaced with overwhelming relief. The key, the key, being the key, yep. That means a lot to you. It does. That's -- that's justice, right. That's justice, that's something we believe in in our family and that coming all together. That's justice. And some of the victims telling us they can finally sleep after a year's long nightmare. Joseph Deangelo has not yet entered a plea and remains on a wheelchair on suicide watch with no bail. I know you'll have much more on the golden state killer on "20/20" on ABC. I'll take it.
This transcript has been automatically generated and may not be 100% accurate.