The search for missing Colorado mom Kelsey Berreth, who is presumed dead, continues — and investigators are looking at a landfill for answers.
“The Colorado Bureau of Investigations contacted Waste Management of Colorado regarding a potential search at Midway Landfill and we are cooperating fully,” a spokesperson for Waste Management told PEOPLE in a statement.
A spokeswoman for the landfill confirmed to ABC News that the search inquiry was related to Berreth’s disappearance.
Berreth, a 29-year-old flight instructor from Woodland Park, has not been seen in public since Thanksgiving.
The spokesperson for the landfill declined to answer questions about the timing of any search or what investigators are looking for.
As of Thursday morning, no law enforcement had been seen at the landfill, according to the Colorado Springs Gazette.
The Colorado Bureau of Investigation and 4th Judicial District Attorney’s Office did not immediately respond to PEOPLE’s requests for comment.
On Thanksgiving of last year, surveillance video captured Berreth and her 1-year-old daughter Kaylee entering a local supermarket. That was the last time she was seen publicly.
In late December, authorities arrested Berreth’s fiancé, Patrick Frazee, who faces two counts of murder and three counts of solicitation to commit murder.
Earlier this month, Berreth’s parents, Cheryl and Darrell, filed a wrongful death lawsuit in Colorado’s federal district court. The lawsuit, which was obtained by PEOPLE, seeks unspecified damages against Frazee for Berreth’s presumed death.
Frazee, who did not live with Berreth, told police that he and his fiancée met up that same day so that Berreth could hand off their daughter to him.
Berreth’s mother, who lives out of state, reported her missing 10 days later, on Dec. 2, 2018.
While Teller County investigators have yet to detail the specific allegations that led to the solicitation counts, it likely means prosecutors think Frazee allegedly solicited an individual three times or three people on three separate occasions as part of an alleged murder plot.
The alleged solicitations occurred between Sept. 1 and Nov. 1, 2018, according to the charging documents, which were obtained by PEOPLE.
According to the charging documents, prosecutors filed two murder counts because they have two theories about how the presumed killing may have taken place: either Frazee killed Berreth by himself, or he and someone else allegedly tried to rob Berreth before she was killed.
• Want to keep up with the latest crime coverage? Click here to get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter.
Frazee remains in police custody without bond. He has not yet entered pleas to the charges, and his criminal attorney could not be reached for comment. It is unclear if Frazee has representation in the civil case.
Authorities are investigating a second person — an Idaho woman — in the case. They believe she might have helped dispose of Berreth’s phone, multiple outlets reported.
Three days after Berreth apparently vanished, Berreth’s mobile phone pinged on a cell tower near Gooding, Idaho, nearly 600 miles from her home, police have said. That same day, texts from the phone of Berreth were sent to her employer, Doss Aviation, saying she would not be at work for the next week.
The status of the Frazee and the woman’s relationship remains something of a mystery, with relatives saying Berreth had ended the engagement weeks before vanishing. Others have claimed Berreth and Frazee split the day of the alleged killing.