Kelsey Berreth, Patrick Frazee

Krystal Lee, a registered nurse who allegedly disposed of a cell phone belonging to her boyfriend’s missing fiancee, has been fired from her job.

Lee, 32, is set to appear in a Colorado courtroom on Friday to plead guilty to at least one count in the disappearance of Kelsey Berreth, a 29-year-old pilot and mom-of-one (pictured above).

A spokesperson at St. Luke’s Magic Valley Medical Center in Twin Falls, Idaho, confirmed to Radar Online that Lee was no longer employed there.

“An individual by that name is no longer an employee of St. Luke’s,” the spokesperson told Radar on Thursday.

Berreth was last seen on surveillance video shopping at a Colorado supermarket with her 1-year-old daughter, Kaylee, on Thanksgiving Day.

Berreth’s mother, Cheryl, reported her missing on December 2 – ten days after she was last seen on surveillance footage at a Safeway supermarket.

Joe and Patty Rockstahl, who own Rockstahl Law Offices, told KMVT they contacted the FBI after one of their employees told them in October that her best friend said, “a man had asked her to kill the mother of his child.”

The Rockstahls say they made the connection to Berreth’s disappearance after watching the news.

Police arrested Berreth’s fiancé and father of her daughter, Patrick Frazee. He was charged with two counts of murder and three counts of solicitation to commit murder. Berreth’s body has not been found.

On November 25, three days after Berreth went missing, her phone pinged off a tower 800 miles away near Gooding, Idaho. Lee lives about 30 minutes from where Berreth’s cell phone last pinged.

That same day, two text messages were sent from the missing mom’s phone. One text message was sent to her employer – Doss aviation, where she was a flight instructor. The message said Berreth would not be in to work for a week. A second text message was sent to Frazee.

Police charged Lee with tampering with evidence for disposing of the cell phone.

Investigators believe Lee sent the text messages from Berreth’s phone before disposing of the phone in Idaho.

Lee, a mother of two, reportedly became romantically involved with Frazee after meeting him at a rodeo. Their families were friends for decades. Police believe Lee helped Frazee after he killed Berreth.

Frazee is being held without bond at the Teller County Jail in Divide, CO. He has not entered a plea to the charges.

Berreth’s parents have filed a wrongful death lawsuit against Frazee, seeking unspecified damages, according to A court granted them temporary custody of 1-year-old Kaylee.

“Kelsey was a kind, sweet girl,” her lifelong friend Ashley Cogburn told CBS News. “She kind of had it all going on. She was, you know, she was really smart. She was on top of her game in life,” Cogburn said. “She was doing it all.”