DENVER, Nov. 27 (UPI) -- In his video confession to slaying 10-year-old Jessica Ridgeway of Colorado, Austin Sigg said he knew the second he pulled her into his car, he would kill her.
Sigg, 18, was sentenced Nov. 19 to life imprisonment for kidnapping, sexually assaulting, killing and dismembering the young girl. He pleaded guilty to 15 counts, including kidnapping, first-degree murder and sexual assault of a child.
Jessica was last seen walking to her Westminster school in October 2012. Her partial remains were discovered five days later in Arvada after Sigg's mother called police, saying her son admitted to the crime.
Police released Sigg's video confession detailing his abduction of the girl.
Sigg said he had never seen Jessica before, and that "she was [in the] wrong place, wrong time," KCNC-TV, Denver, reported Tuesday.
He said he pulled her into the back seat of his car and "zip-tied her hands and feet."
"I would lie to her. I would tell her everything was going to be OK and I would just lie to her," Sigg said. "[But] the second I pulled her into my car, I knew she was dead."
"When she was lying there, all I could think of was, 'Oh God what have I done?'" he added.
During his interview, Sigg became frustrated and allegedly lied when talking about whether he sexually assaulted Jessica, KDVR-TV, Denver, reported. He said he dismembered her body in an attempt to make sure the evidence didn't lead to him.
"The dismemberment was from forensic scientist class. Serial killers and the successful ones were the ones who could always make the body disappear," he said.