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BRIGHTON, Colo. — The man accused of shooting and killing Broomfield teenager Natalie Bollinger agreed to plead guilty to second-degree murder at a hearing on Monday morning to avoid a sentence of life in prison.

Joseph Lopez, 23, said he shot Bollinger, 19, last year after responding to an ad she had placed on Craigslist that she wanted to “place a hit” on herself, according to court documents.

Lopez was charged with first-degree murder. The plea deal calls for Lopez to serve 48 years in prison plus five years on probation.

Bollinger’s family pleaded with the judge during Monday’s hearing to sentence Lopez to life in prison, but that request was denied.

Bollinger’s father, Ted Bollinger, said last month that he did not agree with the plea and proposed sentence.

“We said no and they still offered it to him today,” he said. “Our family does not agree with this or is willing to do any plea bargain. I’m dumbfounded. I’m so disappointed in the legal system in Adams County.”

Bollinger, 19, was reported missing on Dec. 28. Her body was discovered in a wooded area along Riverdale Road near McIntosh Dairy in Adams County the next day.

The Adams County Coroner’s Office said Bollinger died from a single gunshot wound to the head execution style.

According to an Adams County sheriff’s arrest affidavit, investigators alleged Lopez initially denied seeing Bollinger die.

But then Lopez changed his story to say Bollinger killed herself before saying he killed her because she solicited someone on Craigslist to help her commit suicide.

GPS data from Lopez’s phone placed him at the scene, according to the affidavit.

RELATED: Joseph Lopez affidavit

Lopez said Bollinger “knelt down on the ground and that he knelt down along her left side and slightly in front of her.”

He said they said a prayer together before he shot her,  according to the affidavit. Lopez then left the scene with Bollinger’s purse and the gun.

Lopez told investigators that sometime after Christmas, he came upon an ad on Craigslist titled “I want to put a hit on myself” while looking at the “women seeking men” category, according to the affidavit.

Lopez claims the ad was posted by Bollinger.

According to the affidavit, Lopez claims he met with Bollinger and they discussed how she wanted to die. He told investigators she “wanted to be on her knees and executed from behind.”

The affidavit also said Bollinger had a history of heroin and methamphetamine use. The report said at the time of her death, Bollinger had a “potentially lethal level of heroin in the blood.”​

Lopez claims in the affidavit that he tried to talk Bollinger out of it, but that she wanted to end her life because of issues with her boyfriend.