The Idaho nurse involved in the case of missing Colorado mom Kelsey Berreth has been fired from her job at St. Luke’s Magic Valley Medical Center in Twin Falls, Idaho.

The nurse, Krystal Lee, also known as Krystal Jean Kenney, was formally charged with tampering with physical evidence and will appear in a Teller County, Colorado, court on Friday. She is expected to enter a plea of guilty and has allegedly accepted a plea deal with prosecutors, ABC News reported.

Family members told ABC News anonymously that Lee is cooperating with investigators.

When asked about Lee’s employment at the medical center, Michelle Bartlome, a spokeswoman for St. Luke’s, told ABC News that “an individual by that name no longer works at the hospital."

In January, Lee, 32, was placed on a leave of absence after an investigation was started into her involvement in Berreth’s disappearance. Lee is accused of disposing of Berreth’s cell phone which pinged off a Gooding, Idaho, cell tower just three days after her disappearance on Thanksgiving Day.

Berreth was last seen on surveillance footage with her daughter at a Woodland Parks, Colorado, Safeway grocery store. Her fiancé and the father of her daughter, Patrick Frazee, is thought to be the last person to see her alive.

Frazee, who is suspected of having a romantic relationship with Lee, was charged with two counts of murder and three counts of solicitation to commit first-degree murder for Berreth’s disappearance on Dec. 31. 

Berreth is presumed dead by investigators as her body or remains have yet to be found.

The evidence tampering charge that Lee is facing is a class 6 felony that carries a sentence of up to 18 months in prison.

Idaho Nurse Fired The Idaho nurse that is accused of tampering with missing Colorado mom Kelsey Berreth's cell phone has been fired from her job. A woman raises her handcuffed hands during a protest in Turkey, in Ankara, on April 14, 2011. Photo: Getty Images/ADEM ALTAN