Teen Found Guilty Of Murder
A 17-year-old has been sentenced to life in prison after killing his stepsister. Here, a National Park Service ranger walks down the main cell block on Alcatraz Island on June 14, 2007 in San Francisco Bay of California. Robyn Beck/AFP/Getty Images

A 17-year-old from Colorado pleaded guilty last month to first-degree murder after killing his 10-year-old stepsister, and now he has been sentenced to life in prison. Aidan Zellmer will be eligible for parole in 40 years.

Kiaya Campbell and Zellmer were going shopping in 2017 when she disappeared. Zellmer initially told authorities the two got separated during a rainstorm. Campbell’s body was found a day after her disappearance in a drainage ditch, beaten to death and sexually assaulted. She was nude from the waist down, reports Fox6 Now.

Through his plea deal, prosecutors dropped a sexual assault charge, reports 9News, meaning Zellmer has the opportunity to take part in a youth corrective program. If he succeeds, he could be released at age 47.

“In 27 years as a prosecutor, I have never seen a 15-year-old commit such a violent act,” 17th Judicial District Attorney Dave Young said.

“He wanted to do this. His actions certainly dictate that he intended to kill Kiaya Campbell and it took quite an effort to do it. And then to conceal it afterwards, not only trying to hide the body but to mislead the police and everyone that was looking for her body certainly indicates that his brain was developed and he knew exactly what he was doing,” Young continued.