Despite being a cold-blooded killer, Keyes was anxious to protect his reputation.
"He was very, very, very sensitive to his reputation, as odd at that sounds," Anchorage Police Chief Mark Mew told the Associated Press. "We had to keep things extra quiet in order to keep him talking with us."
Authorities had gently been coaxing information from the killer about his other crimes up until he committed suicide alone in his cell on Sunday.
Keyes embedded a disposable razor blade into a pencil and slit his wrist and used bedding material to strangle himself, the FBI said in a statement. He left behind "crumpled, blood soaked paper" with writing on the pages.
It's unclear what clues, if any, remain, leaving authorities with missing pieces of the puzzle they were so methodically putting together.
The FBI is asking for the public's assistance with any information about Keyes' travels in order to identify additional victims. They ask that anyone with information contact the FBI at 1-800-CALL-FBI.