The Adams County Sheriff's Office announced late Thursday night that 22-year-old Joseph Lopez had been arrested on suspicion of first-degree murder in the death of 19-year-old Natalie Bollinger, of Broomfield.
Lopez told police that he met her after responding to a Craigslist post in the "women seeking men" section of the website entitled "I want to put a hit on myself", according to an arrest warrant affidavit on December 28 and met Bollinger for the first time later that day.
Investigators say Lopez told them that he exchanged text messages with Bollinger during which she expressed a desire to be "executed" from behind and offered to bring her own firearm.
The affidavit goes on to say that when Lopez went to her apartment on December 28, she told him that she wanted to be killed "on her knees ... executed from behind", the station reported.
The 19-year-old's body was found on a dairy farm in Adams County on December 28, almost 26 hours after she was reported her missing in Broomfield.
An autopsy report stated that Bollinger had a potentially lethal amount of heroin in her blood at the time of her death.
A weapon was found "around" Lopez, McIntosh said, but it has not been tied to Bollinger's death, according to the Daily Camera.
Loved ones told police Ms Bollinger had a history of suicidal thoughts but had been happy recently.
She allegedly said she was having issues with her boyfriend, who had reported her missing. They then drove around while discussing how he would be paid.
The affidavit states that Lopez told detectives he changed his mind about killing the teen and dropped her back off at her apartment.
Then, he told investigators, he fled with Bollinger's purse and the gun.
Bollinger and Lopez hadn't known each other very long McIntosh said. He said they said a prayer, he got up and closed his eyes and fired the fatal shot. Schwartz said he had been interviewed by police.
The sheriff said it still is unclear whether drugs played a role in Bollinger's death.
Before Lopez's arrest, Schwartz was said to have been connected to the girl's murder although he posted on Facebook that he was innocent.
"At this point, to my knowledge, we don't have any more persons of interest in this case", said McIntosh.
Lopez was arrested after he was interviewed at the Adams County justice center in Brighton. He is in jail with no bond, scheduled to appear in court again on Wednesday in a case that has shaken this part of Colorado since late previous year.