HOUSTON (KTRK) -- Video released in the wake of a guilty plea shows the two sides of a cop killer.
Two weeks ago, Shannon Miles pleaded guilty to the murder of Harris County Sheriff's Deputy Darren Goforth. He was sentenced to life in prison without parole.
Surveillance video from the Cypress gas station where Goforth was ambushed on August 28, 2015 shows one side of Miles. Hours of interrogation video show another side.
Miles: "Anything I can do to help."
It was a calm, cool Miles who sat through hours of questioning, compared to the deliberate and violent one just hours earlier.
TIMELINE: The Shannon Miles Case
Investigator: "Is there something going on? You know. Dr. Jekyll and Mr. Hyde? You know. Am I seeing a different Shannon?"
Miles: "No way. Absolutely not."
The request for the gas station surveillance video by Eyewitness News to the Montgomery County District Attorney's Office, the special prosecutor, did not include Goforth's killing.
It shows a man, later identified as Miles, circling the parking lot in his truck. He parks and then watches the veteran officer exit the store, unaware of what is about to happen.
Miles jumps out of his truck and runs in the direction of Goforth. Off-screen, he shoots him 15 times. Miles walks back to his truck, gun in hand and takes off. Investigators later found the gun and truck at Miles' house less than two miles away.
Investigator: "The murderer was in that truck and used that gun."
Miles: "Nah. I'm not saying that's me. I wouldn't have the faintest clue why that would match up."
Miles' documented mental illness played a huge role in his plea deal, according to both the defense and prosecution.
As he was being interviewed, he never broke and never revealed a motive.
Investigator: "Please. Please. Help me understand. If that man did something to you. I mean. If, if it's just a police thing."
Miles: "I don't know that guy. I don't know anybody over there."
Miles defense attorney told reporters Miles does not remember the night of the murder. The gas station video shows a calculated Miles. The interrogation room video shows a convincing one.
Miles: "I've told you everything I can tell you. I think that's it. I mean, it don't make sense to me because it's senseless."
Miles has been transported from the Harris County jail to the Byrd Unit in Huntsville to start his prison sentence.