Israel Keyes, 34, killed himself Dec. 1 in his Alaska jail cell, abruptly ending an investigation authorities said could have led them to more bodies and crimes, ABC News reported Tuesday.
Police said they have more than 40 hours of taped interviews with Keyes that give them clues on how he managed to go undetected for so long and his motivation for the killings.
Keyes was arrested after allegedly breaking his personal code of conduct in the Feb. 1 kidnapping, rape and killing of Samantha Koenig, 18, ABC News said.
He said he told himself if the person working in the Anchorage coffee shop did not have a car, he would only rob the establishment and leave because he didn't want to transport her body in his car. Koenig didn't have a vehicle, but he attacked her anyway because he couldn't help himself, Keyes told police.
"He basically had this rule, this unwritten rule, that he would travel outside and go to great lengths to distance himself from any of his victims," Anchorage homicide detective Monique Doll said. "He told us he was losing control. He was losing the massive amount of self-control that he had."
The interviews also revealed Keyes' fascination with serial killers -- he knew a lot about Ted Bundy -- though he felt strongly that he not want to be identified as a serial killer himself.
During his robberies, he told police he always took two guns -- one for the robbery, and one for a shootout. Keyes said envisioned himself dying in a shootout with police.