Krystal Lee Kenney is scheduled to appear in a Teller County courtroom in Friday to accept a plea deal from prosecutors

Idaho Nurse Accused of Tampering with Evidence in Case of Missing Colorado Mom Kelsey Berreth

An Idaho nurse has been charged with tampering with physical evidence in the case of Kelsey Berreth, the missing Colorado mom whom authorities presume was murdered.

A summons and separate criminal complaint, both obtained by PEOPLE, confirm Krystal Jean Lee Kenney, 32, of Hanson, Idaho, as the suspect in the felony tampering count filed Monday by prosecutors. The charge is believed to be part of a plea deal to which Kenney will plead guilty Friday in Teller County, Colorado, according to earlier reports.

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Prosecutors in Colorado who already have brought murder charges against Berreth’s fiancé, Patrick Frazee, 32, allege that Kenney “destroyed, mutilated, concealed, removed, or altered physical evidence” in the case “believing that an official proceeding was pending or about to be instituted,” according to the formal charge.

Police have been investigating whether Kenney allegedly dumped Berreth’s phone in Idaho on Nov. 24 or 25, where the missing mom’s mobile device last pinged off cell towers shortly before authorities launched a search for her.

A spokeswoman for District Attorney Dan May would not discuss the plea deal with KOAA, but she did confirm Kenney’s court appearance.

In charging documents obtained by PEOPLE last month, prosecutors state they believe the suspected killing of 29-year-old mother was planned over two months — allegedly by Berreth’s fiancé, Patrick Frazee, who stands accused of murder.

In addition to two counts of murder, Frazee, 32, faces three counts of solicitation to commit murder in the death of his still-missing fiancée, who is the mother of his 1-year-old daughter.

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While Teller County investigators have yet to detail the specific allegations that led to the solicitation counts, it likely means prosecutors think Frazee allegedly solicited an individual three times or three people on three separate occasions as part of an alleged murder plot.

The alleged solicitations occurred between Sept. 1 and Nov. 1, 2018, according to the charging documents, which were obtained by PEOPLE.

According to the documents, prosecutors filed two murder counts because they have two theories about how the presumed killing may have taken place: either Frazee killed Berreth by himself, or he and someone else allegedly tried to rob Berreth before she was killed.

The five charges Frazee faces were filed nearly a month after Berreth disappeared without a trace. Officials believe Berreth was killed, but have yet to find her remains.

Berreth, a flight instructor from Woodland Park, hasn’t been seen in public since Thanksgiving when surveillance video captured her and her daughter entering a local market.

Frazee, who did not live with Berreth, told police that he and his fiancée met up that same day so that Berreth could hand off their daughter to him.

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Berreth’s mother, who lives out of state, reported her missing 10 days later, on Dec. 2, 2018.

Frazee was arrested on Dec. 21, 2018, without incident on suspicion of first-degree murder and solicitation to commit first-degree murder. He remains in police custody without bond.

Authorities have not discussed a possible motive for the presumed killing.

The couple’s daughter had been staying with Frazee after Berreth disappeared but is now with Berreth’s family, authorities announced.

Three days after Berreth apparently vanished, her mobile phone pinged on a cell tower near Gooding, Idaho, nearly 600 miles from her home, police have said.

That same day, texts from the phone of Berreth were sent to her employer, Doss Aviation, saying she would not be at work for the next week.

The status of the Berreth and Frazee’s relationship remains something of a mystery, with relatives saying she had ended the engagement weeks before vanishing. Others have claimed the couple split the day of the alleged killing.