He prided himself in his ability to maintain a double life and was very cautious about protecting the life he led with his girlfriend and daughter.
"He was very confident in that fact that he was successful in leading this kind of Dr. Jekyll and Mr. Hyde lifestyle and that no one would ever suspect him of doing these crimes, had he not confessed," Doll said.
As a killer, he was remorseless and made it clear that he liked to kill.
"Israel Keyes never expressed in any way, shape or form that he was ashamed or regretted any of his actions and he was very self-aware. He was also very okay with the fact that he did this because he got enjoyment out of it," she said. "He didn't try to rationalize it."
Authorities also released new audio from interrogations with Keyes. In both clips, he described failed plans to kill other Alaskans from April and May 2011.
In one case, he had staked out a park where a young couple were in a car. The assassination was interrupted by an Anchorage police officer who showed up to tell the couple the park was closed.
"It could have got ugly, but fortunately for the cop guy..." Keyes said before chuckling, "his backup showed up. I mean, APD is really good. They're really good, like all by the book and stuff. That's about the time I decided to get a scanner because I almost got myself into a lot of trouble on that one."
That would not be Keyes' last close call.
After he abducted, raped and dismembered Koenig, he took off to the southern U.S. with her debit card, which he used at several ATMs before being caught in Texas. Authorities said Keyes knew the risk he was running, but wanted to fulfill a fantasy of executing a ransom where the money was deposited into a debit account he would use.
"Using her debit card was part of his fantasy and it was something that he had thought about for a long time," Doll said. "He had also thought about how he was going to cloak it, how he was going to escape law enforcement. He wasn't a stupid man."
"He had understood that a debit card and a debit card usage is a very easy way for us to track somebody's movement, but...that was part of his fantasy that he wanted to fulfill," she said.
If Keyes had not decided to risk it with the debit card, he would likely still be traveling to kill. He told authorities that he intended to leave Alaska this summer and would probably work as a gypsy contractor while keeping up his fatal hobby.
"I don't think he had any intention of stopping what he was doing," Bell said.
The FBI in Oregon is asking for help identifying Keyes' potential first victim. Keyes told FBI agents in Alaska that he raped but did not kill his first victim in Oregon between 1996 and 1998. He said the girl was between 14 and 18 years old.
The FBI is asking that anyone with information about Keyes contact the FBI at 1-800-CALL-FBI.