Tonight, the newly released tapes granting an astonishing look at the twisted mind of a serial killer. From jack the ripper to john wayne gave see, murders who seem to chose their victims at random... See More
Tonight, the newly released tapes granting an astonishing look at the twisted mind of a serial killer. From jack the ripper to john wayne gave see, murders who seem to chose their victims at random fascinate and terrify us. It was the disappearance of an 18-year-old alaskan girl that led to police unravel one such killer's astounding 11-year killing spree. Neal karlinsky brings us the chilling details for our series, "crime and punishment." Reporter: You're watching 34-year-old israel keyes describe over coffee and a bagel his strategy for hunting and killing innocent people. Back when I was smart, i would let them come to me. Just a remote area. Kind of go to a remote area that's not anywhere near where you live. But that other people go to, as well. Reporter: The police interrogation is in anchorage, alaska, where keyes was being held for the killing of samantha koenig, seen her putting her hands up the very moment a masked keyes pulls a gun on her. He leads her away from the coffee stand, telling police he killed her and left to take a cruise out of new orleans before asking her family for ransom. Gruesome as it is, keyes wasn't done talking. In fact, the man who matter of factually confessed to raping and murdering koenig, left investigators stunned by telling them he's a serial killer. There is no one who knows me or who has ever known me who knows anything about me, really. We spent a fair amount of time talking about his offenses, and those times were definitely very chilling to hear him talk about what he had done. Reporter: Fbi special agent jolie goeden interviewed keyes over a period of months, sitting in the same room with a man she now believes to be a real life monster. Very meticulous. Very organized. He definitely planned everything he did. Reporter: Keyes traveled the country from alaska to vermont, looking for people to kill, totally at random. And funding his crimes by robbing banks. The fbi has now retraced his steps. A long list of dates and locations since 2001, when they believe he may have killed repeatedly. They so far have eight confirmed murders and rapes, including a couple in essex, vermont, four in washington state and one more on the east coast with a body hidden in new york. And he told agents something they'd never heard before. That he left kill kits or caches, buried in several states, filled with everything he'd need to commit a murder. They were in waterproof containers and included guns and different things he could use to dispose of bodies. His strategy, to grab people in remote locations, like parks, caounds, even cemeteries. Every serial killer, including, I believe, mr. Keyes, are not crazy. You cannot be that organized and deliberate and fit any legal definition of insanity. You might not get exactly -- not as much to choose from, in a matter of speaking, but -- there's always no witnesses, really, there's nobody else around. Reporter: Investigators say keyes is a text book serial killer. Like others in the past, he took pleasure in the act of taking a life. He talked about the rush that he got out of it. The adrenaline and kind of the high from doing it and I think, unfortunately, I think he enjoyed what he was doing. There is nothing probably greater than holding the power and control of someone's life and looking them in the eye and being able to control all of that. Is intoxicating to serial killers. And that's why they keep doing it. Reporter: Keyes told the agent he could relate to ted bundy, who confessed to 30 murderers before being executed in 1989. The two killers had similar methods. It's very common for serial killers too relationship with the individuals they killed. Many times they will not do it in their own community. Mr. Keyes, ted bundy fits this profile. Reporter: Prolific serial killers carefully. But I always thought I was doing you guys a favor, killing prostitutes. Reporter: Ridgeway was convicted of 49 murders and confessed to even more. How do you plead to the charge of aggravated murder in the first degree as charged in count 45? Guilty. Reporter: Like ridgeway, keyes seemed to enjoy slowly revealing his secret. I'm two different people, basically. Reporter: How long have you been two different people? Long time. 14 years. Reporter: Keyes said enough to start a massive investigation, but he didn't tell them everything. Sunday, they found his body. He'd killed himself with a razor inside his jail cell. One final act of control. I'm neal karlinsky for "nightline" in seattle.
This transcript has been automatically generated and may not be 100% accurate.