Murder suspect alleges teen put ad on Craigslist for a hit man to kill her Joseph Lopez, 22, was arrested in 2017 slaying of Natalie Bollinger, 19.

 -- The man accused of killing a Colorado teen in December said she placed an ad on Craigslist for a hit man to kill her because she wanted to die, according to court documents.

Joseph Lopez, who was arrested last Thursday and charged with first-degree murder in the killing of Natalie Bollinger, 19, told police he was looking through the "Women seeking Men" category on Craigslist "when he saw an unusual post titled, 'I want to put a hit on myself,'” according to the probable cause affidavit.

Lopez, 22, said he responded to the ad and, by 2 or 3 a.m. Dec. 28, he was emailing with the woman, who was later determined to be Bollinger, the affidavit said. They started texting later that morning and exchanged about 111 texts within three hours, the affidavit said.

Because he struggled with depression and suicide attempts, Lopez told police, he used "a fake persona of a hit man that he had created for himself," and said he talked to Bollinger using that persona to convince her he was a hit man and willing to help her commit suicide, the affidavit said.

Lopez explained to police that he has an app on his phone that lets him create "fantasy personas;" he said one of the 12 personas has a "charismatic" backstory who "can lure people in but then he turns 'psycho' and he strikes,'" the affidavit said.

Over text, Lopez said, he used the persona "and agreed to meet her and kill/assist her in her suicide," according to the affidavit.

Lopez said they communicated about "how she wanted to be shot and killed and that she wanted it to happen 'quickly,'" the affidavit said. He said Bollinger said she "wanted to get on her knees and be executed from behind because she did not want to see the gun," according to the affidavit.

Lopez told investigators Bollinger asked how much it would cost for him to kill her and he said he told her "from hundreds to thousands. It just depends," the affidavit said.

Lopez said she asked whether he had a gun and he said no, so Bollinger allegedly offered to bring hers and said he could keep it to sell if he wanted, according to the affidavit.

Lopez said he got to her apartment around 11 a.m. or noon and in the car "they continued to talk about how her death would happen," the affidavit said. Lopez told police "he was only talking to her about it until he gained her trust and then he would try to convince her that it was a bad idea and that she shouldn't do it."

Lopez said Bollinger told him "she needed to get away from her boyfriend because he was bad for her," the affidavit said. Lopez also alleged that the woman appeared "upset" and told him about how she loved her boyfriend and "did not want to leave him or hurt him."

According to the affidavit, Lopez initially told police they drove to a few places for the shooting but Bollinger didn't like those spots, so he drove her home and dropped her off at a gas station; Lopez said that was the last time he had contact with her, the affidavit said.

Lopez later told police that at one point Bollinger got out of the car, pulled the gun out of her purse and held it to her temple; Lopez said he tried to talk her out of it but "before he could grab the gun from her she shot herself in the left temple causing her to fall backwards against the tree," the affidavit said.

He said he "panicked" and took her purse and gun and fled, the affidavit said.

Police then, according to the affidavit, told Lopez they knew the gun was between 1 and 3 feet away during the shooting and that, according to the autopsy, she was killed by someone else.

So Lopez changed his story and said the teen "convinced him to help her kill herself," the affidavit said.

Lopez told police they parked the car and walked over to the trees, knelt down and said a prayer together; he said, shaking, he held the gun with both hands, closed his eyes and fired one round hitting Bollinger in the head, the affidavit said.

Lopez told authorities he panicked, grabbed her purse, went home and hid the gun and purse in his trunk, the affidavit said.

Lopez's co-worker at Domino's Pizza told investigators he called in sick at 6 p.m. Dec. 28, an hour after he was supposed to arrive at work, the affidavit said.

According to the affidavit, the accused man said "it was eating away at him" and he had considered calling the police to confess.

Bollinger's father, Ted Bollinger, told ABC News his daughter today was a "good girl" who had a full scholarship to the University of Colorado-Boulder.

She was going to start this semester, he said.

Instead, he's now going to Lopez's court appearance Wednesday.

"We need to represent Natalie," he said.

Lopez has not yet entered a plea. His public defender did not immediately respond to ABC News' request for comment.