"As soon as the video camera went on, we saw obvious human remains," said former FBI Special Agent Bobby Chacon.

On February 1, 2012, Alaska serial killer Israel Keyes kidnapped 18-year-old barista Samantha Koenig at gunpoint from Common Grounds Espresso in Anchorage. He then took her to a shed on his property where he sexually assaulted and strangled her to death. Keyes later told FBI agents that he blasted loud music during the attack so his girlfriend and young daughter, who were inside the house next door, wouldn't hear Koenig's screams.

Keyes explained that weeks after the murder, he dismembered her body and dumped her remains in the deepest area of Matansuka Lake near Palmer, Alaska. He told the FBI that he had cut a hole in the frozen lake under the guise of ice fishing.

Assistant US Attorney Frank Russo told Oxygen's two-hour special “Method of a Serial Killer,” “So I asked him … ‘Did you catch any fish?’ And he said, ‘Yeah I caught a fish.’ And I go, ‘What’d you do with them?’ And he goes, ‘I took them home and ate them.’ So that really kind of turned my stomach[.]"

The day after Keyes’ confession, the FBI dispatched its cold water dive team to Matansuka Lake to recover Koenig’s body.

"We get to Lake Matansuka and some FBI agents, they're kind of standing watch over a spot on the lake that Keyes had directed them to,” former FBI Special Agent Bobby Chacon told "Method of a Serial Killer." “It was a fishing hole that was frozen over. I looked at that and I said, 'If she's here, we're gonna find her.'"

Chacon explained the team then sent out an underwater robotic vehicle to search the fishing hole.

"As soon as the video camera went on, we saw obvious human remains," said Chacon.

He continued, "As a diver, when you first place your hands on that person underwater to bring them home, you start to get a feeling that this is now beyond evidence in a case because we are the first people to put our hands on that victim since the killer. You're happy, but how happy can you be when you've got a dismembered girl in front of you?"

To hear more about Israel Keyes and his eventual capture, watch "Method of a Serial Killer" on Oxygen.

[Photo: "Method of a Serial Killer" Screengrab]