BRIGHTON, Colo. (CBS4) – The teenager who pleaded guilty to killing 10-year-old Kiaya Campbell in Thornton in 2017 was sentenced to life in prison with the possibility of parole. Aidan Zellmer, 16, was sentenced on Monday morning.

Zellmer was 15 at the time of the shocking Adams County crime. He pleaded guilty last month to the murder and will be eligible for parole after 40 years.

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Aidan Zellmer (credit: CBS)

Zellmer was with Campbell the night she disappeared in June 2017. His mother was in a relationship with Campbell’s father at the time.

Kiaya Campbell (credit: CBS)

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Zellmer had claimed the two had been separated in a rainstorm and a search was launched for her. Campbell’s body was found the next day in a drainage ditch behind homes near 128th Avenue and Jasmine Street. The Adams County Coroner’s Office found she had been beaten to death.

“He wanted to do this… His actions certainly dictate that he intended to kill her and it took quite an effort to do it. And then to conceal it, not only to hide the body but mislead. Certainly indicates that his brain was developed and he knew what he was doing,” said Adams County District Attorney Dave Young.

(credit: CBS)

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As part of his plea agreement deal, he’ll be in a youth detention facility until he’s 18 and continue a prison term after that. His family is hopeful he’ll get into a juvenile offender program for minors tried as adults with lengthy sentences. That could bring his eligibility for parole down from 40 years to 30 years.