A Colorado teen is in jail awaiting a first-degree murder charge after police say he killed a woman as she slept and later claimed he thought she was his father after gender reassignment.

The New York Post reported that 19-year-old Joseph Saur turned himself in Sunday after he shot Patricia Stewart, 28, multiple times.

Saur was “clearly under the influence of some kind of drug,” according to an affidavit cited by the Montrose Press.

Investigators say he entered a camper parked in Olathe, where Stewart was sleeping that night. He allegedly shot her in her face a number of times.

He left the murder scene and confessed to authorities, according to the KUSA, but said he thought the victim was his father, who had undergone surgery to become a woman in an effort to “keep from being caught.”

The Press referenced a police report indicating Saur said his father had “done bad things” and that the shooting had been in self-defense.

According to the affidavit, Saur asserted that his father “had a sex change and is now Patience Rian Stewart.”

Investigators found Saur’s father, who expressed concern about the teen, claiming he has been using methamphetamine. The suspect reportedly denied drug use in an interview with investigators.

Police say he provided a detailed account of the shooting and led them to Stewart’s body.

Reports indicate she was in an upper bunk inside the camper and had obvious facial wounds.

About an hour before Saur surrendered, authorities received a report of a shooter walking on a camper roof in the same area officers found Stewart’s body, according to KUSA.

[Featured image: Montrose County Jail]