Koenig is seen putting her hands up several times, and at some point Keyes makes her turn off the light. The light switch was close to a panic button, but Koenig never pushed it, probably because she was too afraid, police said.
The video shows Keyes using zip ties to bind Koenig's hands behind her back, and leading her out. He told Koenig he would let her go if her family paid a ransom, but that was never his intention, police said.
"He knew all along he was going to kill her," Anchorage homicide Detective Monique Doll said.
Koenig's body was recovered from the lake in April after Keyes told authorities where he put it.
The other video shows a man identified as Keyes getting out of a white pickup truck parked in nearby parking lot just before the abduction took place, and returning with another person he appeared to be gripping tightly.
Police said Tuesday a license plate, green toolboxes and a ladder rack had been removed from the truck before the abduction, then reinstalled afterward so Keyes could disguise the vehicle, which had an extended bed.
In their investigation, the vehicle appeared twice in a list of 750 local white trucks of the same kind, but police scratched it off the list of possibilities because it looked so different.
Authorities say Keyes traveled extensively in the U.S., landing at one location and targeting victims randomly hundreds of miles away. Keyes told authorities he robbed several banks and used money he made as a general contractor to pay for his travel.
In the Koenig case, he stuck to his own town.
"He broke his own rule," Doll said.