The teenager who admitted to killing 10-year-old Kiaya Campbell in June 2017 will go to prison for a minimum of 40 years, according to sentencing in Adams County District Court March 11.

Aidan Demmie Zellmer, 17, was given the maximum sentence in court by Judge Sharon Holbrook — a life sentence with a possibility of parole after 40 years.

Zellmer pleaded guilty Feb. 1 to one count of first-degree murder after deliberation in the death of Campbell, the ten-year-old daughter of Zellmer's mother's then-boyfriend, Jacoby Campbell.

According to the arrest affidavit released by the court on March 11, Campbell and Zellmer were last seen leaving the house they shared on 124th and Forest Drive at 7:30 p.m. June 7, 2017.

Campbell's body was found about a mile-and-a-half northeast at 5:30 p.m. June 8.

According to the affidavit, she died of blunt force trauma to the head — at least five blows, which caused skull fractures — and bruises and abrasions on other parts of her body, including defensive wounds. She had been found partially clothed, with her underwear pulled down.

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

According to a statement from the District Attorney's office, Zellmer told police the two had been walking to the west of their home. He “...mislead police, directing them to areas of Thornton away from where he had left Kiaya after murdering her,” Young said in the statement.

Zellmer, who was 15-years-old-at the time, was charged and sentenced as an adult.

“It is important for Mr. Zellmer to acknowledge that he is the only one responsible for Kiaya Campbell's death,” Young said in the statement.

“He is not a victim in this case,” Young said. “Everyone in this courtroom is a victim of this case. Everyone who spent hours and hours looking for Kiaya Campbell's body are victims in this case.”

Stealing Pokemon cards

According to the arrest affidavit, Zellmer told police that he had damaged some of Campbell's Pokemon cards but had planned to steal new ones from a grocery store to replace them.

The two left his mother's house at 7:30 p.m., and went to the shopping area at 120th and Colorado Boulevard. The Pokemon cards were locked behind a counter, so Zellmer told police he shoplifted three bags of candy — one for him, one for Campbell and one for his brother, who had stayed at home. The pair returned to the house, collected a backpack and water and decided to try their luck at the King Soopers at 136th and Colorado.

Zellmer told police they didn't reach that store, however, and turned onto the Heritage Trail walking path at about 129th and Colorado Boulevard to wait out a rain storm before turning back. Zellmer told police he lost track of Campbell that point and began looking for her.

When the pair hadn't returned before midnight, Zellmer's mother called police while the family drove the area searching for them. Campbell's father later found Zellmer walking along Fairfax Street, just south of 128th Avenue — directly north of the house.

Zellmer would later ride with police to areas west of the house, telling police the pair had walked up and down Colorado Boulevard, according to the affidavit.

Security cameras to the northeast showed the pair walking elsewhere, however.

A camera outside of the North Suburban Medical Center at 128th and Holly captured them walking past at 8:11 p.m. and a camera outside of the Wal-Mart at 128th and Quebec showed them there at 8:51 p.m.

Campbell's body was found roughly in between those two camera sightings, in a greenbelt at about 128th and Jasmine Court.

“After striking her five times win the head with a metal pipe, he left her in a field,” Young said in his statement. “When he talked to police, he was calm, cool and collected. He misled and deceived police who were looking for her. This is a rare case. Thank God we don't have other 15-year-olds doing what he did.”