Keyes (right) recently killed himself in his jail cell.
He confessed to abducting Samantha Koenig (below) Feb. 1 at the Anchorage coffee stand where she worked after he climbed in the drive-thru window.
He bound her with zip ties, and then waited with his victim on the floor of the darkened structure, said homicide police Detective Monique Doll.
"What we found when we interviewed Mr. Keyes was that he knew that the coffee kiosk closed at 8 p.m. and he knew that because Samantha didn't have a vehicle there, somebody was going to come and pick her up," Doll told The Associated Press. "He was waiting for her ride to come there because he intended to take that person as well."
Doll said she doesn't know why Keyes changed his mind about also killing the boyfriend, as he had targeted a Vermont couple he killed last year.