A Colorado teen pleaded guilty to brutally killing a 10-year-old girl whose mother was dating his father.

Aidan Zellmer, 16, was charged with first-degree murder in the death of Kiaya Campbell, who was discovered face-down in June 2017 in a Thorton park, the Denver Post reported.

The teen entered the guilty plea for Campbell’s beating death Friday in Adams County District Court.

“The emotions, in this case, have been high and quite frankly legitimately so,” Judge Sharon Holbrook told the courtroom.

Campbell went missing while on a walk with Zellmer from her father’s home, prosecutors said.

Zellmer told police the 10-year-old was separated from him during a thunderstorm — although some neighbors disputed whether it rained the night she vanished.

The girl’s body was discovered by authorities the next day in a wooded area about a mile and a half from where she disappeared.

An autopsy report revealed she suffered a number of horrific injuries, including open lacerations on her head and skull fractures.

Authorities arrested Zellmer two days later and charged him as an adult.

The teen is scheduled to be sentenced March 11 and faces life in prison with a chance for parole.