A woman has pleaded guilty to a charge that she tampered with evidence connected to the disappearance of a Colorado woman and has agreed to testify against the man charged with killing her.

Krystal Jean Lee Kenney entered the plea Friday to the charge related to the death of Kelsey Berreth, who was last seen on Thanksgiving.

This undated booking photo provided by the Colorado Springs Police Department shows Krystal Jean Lee Kenney. Kenney, 32, has pleaded guilty, Friday, Feb. 8, 2019, to a charge that she tampered with evidence connected to the high-profile disappearance of a Colorado woman. Kenney entered the plea Friday, Feb. 8, 2019 to the charge related to the death of Kelsey Berreth, who was last seen on Thanksgiving. (Colorado Springs Police Department via AP)

PARENTS OF MISSING COLORADO MOM KELSEY BERRETH KEEP CUSTODY OF CHILD AS CRIMINAL INQUIRY PROGRESSES

Prosecutors in December charged Berreth's fiance, Patrick Frazee, with murder and solicitation of murder in the 29-year-old woman's death.

Kenney is from Hansen, Idaho and has agreed to testify against Frazee. She will be sentenced after Frazee's trial and after anyone else prosecuted.

Police have not found Berreth's body but have said evidence suggests she was killed at her home in a mountain town near Colorado Springs on or around Thanksgiving.