Detectives investigating the alleged murder of a Colorado mother are looking into a new lead hundreds of miles away. Sources tell CBS News that officials are investigating an Idaho woman for her possible role in Kelsey Berreth's disappearance in November. Berreth's fiancé, Patrick Frazee, has been charged with her murder.

We're not releasing the name of the 32-year-old nurse from Twin Falls, Idaho, who police are looking into since she hasn't been charged, but police believe she may have helped Frazee cover up the alleged murder by disposing of Berreth's cell phone, reports CBS News' Nikki Battiste. Details of their relationship are unclear, but they reportedly knew each other for years.

Investigators believe Frazee – a blacksmith – murdered the 29-year-old flight instructor around Thanksgiving Day in her Colorado home. The engaged couple did not live together, but have a one-year-old daughter, Kaylee. Berreth was last seen on store surveillance video with their baby the day she vanished.

Three days later, police say Berreth's cell phone pinged nearly 600 miles away in Gooding, Idaho. Several texts from the phone were sent, including one to her employer saying she would be away for a week and another to Frazee.

District Attorney Dan May said investigators do not believe Frazee acted alone. He's charged with five counts, including two counts of first degree murder.

"We filed under two theories, one is deliberation murder and the other is felony murder … we also have three separate counts of solicitation," May said.

So far, no other suspects have been named and Berreth's body has not been found.



Meanwhile, a separate legal battle is brewing over custody of Kaylee. Frazee walked into a Colorado courthouse Thursday as his mother fights Berreth's parents for custody of their granddaughter.

Berreth's parents have temporary parental rights and are caring for Kaylee at their Idaho home. A hearing is scheduled Friday over the release of Frazee's arrest warrant affidavit, which prosecutors have sealed citing an ongoing investigation.