The Idaho nurse who reached a plea agreement in relation to the disappearance of Colorado mom Kelsey Berreth, is set to appear in Teller County Court on Monday. Krystal Kenney, 32, agreed to testify against Patrick Frazee, who is believed to have killed Berreth, his fiancée.

Kenney pleaded guilty in February to one count of tampering with physical evidence linked to Berreth's disappearance. She is facing anywhere from probation to three years in prison. Kenney told police that Frazee asked her to come to Colorado to clean up the crime scene after he allegedly beat Berreth to death, according to court testimony from Colorado Bureau of Investigation Agent Gregg Slater.

“I learned that Patrick Frazee had committed a homicide on approximately Nov. 22, 2018, in Teller County. I knew that law enforcement would be investigating that crime. I moved the victim’s cell phone with the intent to impair the phone’s availability in the investigation. I had no right or authority to move the victim’s cell phone. That occurred between Nov. 24 and Nov. 25, 2018, in Teller County," Kenney said while reading a statement in court in February, according to Reuters

Frazee has been charged with two counts of first-degree murder, three counts of solicitation to commit first-degree murder, one count of tampering with a deceased human body, and two counts of a crime of violence. In May, he entered a “not guilty” plea at his arraignment hearing. His trial is set to start in October, and he remains in custody without bond.

Colorado Mom Arrest The fiance of missing Colorado mom Kelsey Berreth was arrested and charged with an investigation of first-degree murder charge. Pictured: A handcuffed man at the police headquarters in Lille, northern France, on Nov. 29, 2018. Photo: Getty Images/PHILIPPE HUGUEN

Berreth, a mother of one, was reported missing by her mother Dec. 2. She was last seen shopping on Thanksgiving Day and three days later, her cell phone pinged near Gooding, Idaho, 40 miles from Twin Falls. While her body or remains have not been found yet, police believe Berreth was murdered at her Woodland Park home. Frazee was the last person to see the 29-year-old flight instructor before she disappeared. 

Authorities searched a Colorado landfill for two months after Kenney told investigators that Frazee disposed of Berreth’s body either in a landfill or river. The Midway landfill is a roughly 40-mile drive from Woodland Park, where Berreth was last seen.

Last week, prosecutors requested permission from a judge to do consumptive testing for DNA on a tooth fragment they believe belonged to Berreth. The fragment was found during the search of Frazee’s property.