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Idaho nurse pleads guilty to tampering with evidence in case of missing woman Kelsey Berreth

"I moved the victim's cellphone with the intent to impair the phone's availability in the investigation," the 32-year-old nurse said in a prepared statement.

The Idaho nurse suspected of tampering with evidence in the case of missing Colorado woman, Kelsey Berreth, reached an agreement to plead guilty in court on Friday.

Krystal Jean Lee Kenney, 32, stated in Teller County court in Colorado that she will testify against Patrick Frazee, Berreth's fiancé, who has been charged with her murder.

As part of the plea agreement, Kenney will not be allowed to speak with media, the judge said during the hearing Friday.

Kenney in a prepared statement said: "I learned that Patrick Frazee had committed a homicide on approximately Nov. 22 in Teller County."

"I knew that law enforcement would be investigating that crime," she continued in the statement that was read aloud by the district attorney at a news conference after the hearing. "I moved the victim's cellphone with the intent to impair the phone's availability in the investigation."

She went on to say that she "had no right or authority" to dispose of or move Berreth's phone.

Berreth's parents in a statement provided by their lawyer said they "are thankful to law enforcement and the District Attorneys for continuing to diligently work on the case and bring the facts to light."

The 29-year-old mother was last seen on Thanksgiving Day, shopping with her 1-year-old daughter, Kaylee. Police have not yet discovered her body but believe she is dead.

Search warrants were issued in Twin Falls, Idaho, in December after Berreth's phone last pinged on Nov. 25 in Gooding, Idaho, more than 700 miles away from her home, law enforcement officials told NBC News.

Frazee, was arrested and charged with Berreth's murder on Dec. 21, shortly after investigators searched his home. Prosecutors believe he either killed the mother of his child or that she died during a robbery he may have committed between Sept. 1 and Dec. 1.

Under Colorado law, if a person dies during the commission of a crime is it is equivalent to murder, District Attorney Dan May said in December.

Frazee told investigators he last saw Berreth on Nov. 22 when she left their daughter with him. The two did not live together. He also said their last communication was Nov. 25, when she sent him a text message.

Doss Aviation, where Berreth worked as a flight instructor, also said that the last time they heard from her was on Nov. 25 — when she texted asking for time off.

Berreth wasn't officially reported missing until Dec. 2, by her mother, Cheryl, who told NBC's "Today" show that her daughter never mentioned any travel plans. She said when the two talked last on the phone on Thanksgiving they discussed a recipe and Christmas.

The couple's daughter remains with Berreth's parents after a court ruled Thursday against Frazee's mother's attempt to gain custody.

Frazee has not yet entered a plea in the case and is expected back in court on Feb. 19. All the affidavits in the case against him are sealed, so it has remained unclear what evidence the prosecution has against him.

Sentencing for Kenney will not occur until the trial against Frazee has been completed, according to court testimony on Friday.