Capturing Israel Keyes took the work of local, state and federal authorities in multiple jurisdictions across the country. Gaining the trust of a cold-blooded killer was a delicate balancing act.
"Sometimes he was more willing to discuss things and sometimes he wasn't, and that was really under his control," said Kevin Feldis, the U.S. Attorney for Alaska. "He could stop talking to us any time he wanted to."
Investigators were at his mercy. Keyes' bargaining chip-- 14 years of secrets about countless unsolved murders, cases authorities want to close.
"The level which he operated was probably more evil than anyone they had ever seen," said Frank Russo, the assistant U.S. Attorney for Alaska.
After his April arrest for the abduction and murder of Alaskan teenager Samantha Koenig, investigators began to build a rapport with Keyes and got him talking about his calculated kills.
"He described that he had a fairly normal childhood and this was a proclivity that he always had, enjoying watching things suffer," Russo said.
Keyes told them his first murder was soon after he left the military in 2000, claiming he'd killed at least eight people since then and hinting there may be more. Investigators say the scariest part was how competent and reasonable he was.
"It would be just like talking to one of us across the table, but it would be this person who had another side to him that enjoyed killing people," Russo said.
Investigators say while questioning Keyes about Koenig, he admitted to murdering a Vermont couple. Bill and Lorraine Curriers' disappearance lined up with his story.
"We had a strategy going there to convince him that it was in his interest to tell us about the Curriers," Russo said.
The feds say they outlined the evidence they had against him, showing him what they planned to prove in court. It worked.
"He basically took out a Google map and told us where they were buried. And then went into details with investigators later on as to what happened to Bill and Lorraine Currier," Russo said.
But when it came to his four unidentified victims in Washington and one in New York, authorities had less leverage. With Keyes facing life in prison, it appeared they would have years to chip away at him. His suicide changed the game.
"It's very difficult to find out who's missing in the United States among adults at any given time, and it was one thing that frustrated us and frustrated the FBI," Russo said.
Prosecutors are now focused on his paper trail. They've subpoenaed airlines, car rental and credit card companies to physically plot out where he's been. They say the biggest challenge is that Keyes would go dark for periods of time to avoid detection. The FBI compiled a rough timeline of his travels that shows 35 trips throughout the U.S., Canada and Mexico. They've also released video clips of Keyes, hoping they trigger someone's memory and lead to clues about his other killings; remorseless murders he told prosecutors he did not regret.
"His only regret was that he didn't kill more people while he was out of jail," Russo said.
If anyone has any information concerning Keyes or his travels they're urged to call federal authorities at 1-800-CALL-FBI and follow the prompts for Israel Keyes.