The mystery of a Colorado teen's death may finally be coming to an end; police say a 22-year-old has been charged for the killing.

According to earlier reports, Natalie Bollinger's body was discovered in a remote area just outside Denver on December 29, 2017. The 19-year-old's family reported her as missing the previous day.

Bollinger had recently posted a warning to Facebook about her accused stalker, prompting police to initially focus on him as a person of interest.

Until another man confessed to the crime, according to ABC Denver.

Natalie Marie/Facebook

On Friday, Adams County Sheriff Michael McIntosh announced at a press conference that 22-year-old Joseph Michael Lopez was arrested on suspicion of first-degree murder for Bollinger's death.

And now, a newly released affidavit has revealed some disturbing details about the day she died.

According to the document, Lopez told police that he started speaking to Bollinger after coming across an ad she posted in the “Women Seeking Men” section of Craigslist.

He claims that the teen was seeking somebody to execute her and was willing to pay them. ABC Denver reports that she wrote:

“I want to put a hit on myself."

Lopez responded and said he exchanged texted with the victim about the possible execution. He claims she asked to be “on her knees… executed from behind."

Police say that the two sent more than 100 text messages to each other the night she disappeared.

Adams County Sheriff

Lopez told police that he tried to talk her out of it but eventually agreed to take her to a remote area, where he shot her at close range in the back of the head with a gun she provided.

GPS data collected from his phone placed him near the crime scene, police said.

The coroner's report confirmed she died from a single gunshot wound and also had a “potentially lethal level of heroin in the blood at the time of death,” the Daily Camera reports. According to ABC Denver:

The autopsy report notes Bollinger had a “history of heroin and methamphetamine use,” after revealing she died from gunfire. Lopez told investigators that at no time did “they have or consumer any type of drugs.”

However, the teen's mourning family thinks that Lopez's story is a lie. According to the Daily Beast, her sister said:

“This man is covering up lies. Only even worse than lying, he’s making my sister look crazy. It’s disgusting.”

Lopez is currently being held without bail. Police said that despite the arrest, the investigation is still on-going.