The fiancé of Colorado mom Kelsey Berreth has been arrested for an investigation of first-degree murder charge, The Denver Post reported.

The arrest warrant was served for Patrick Frazee early Friday morning. Berreth has been missing since Thanksgiving Day, and Frazee is believed to be the last person to have seen her.

Police arrived at Frazee’s home for the arrest and transported him to the Teller County Jail, the Daily Mail reported. A search is underway at Frazee’s property by the FBI and CBI.

A source close to the investigation told the Daily Mail that the arrest of Frazee came after new information was obtained by authorities that gave them a reason to believe that Berreth is no longer alive.

Frazee, 32, is the father of Berreth’s daughter Kaylee. The two are not married and do not live together.

Authorities in the investigation searched Frazee’s 35-acre property last week, returning to the home on Monday for a routine check. No arrest was made at that time. On Thursday night, officials were at Berreth’s townhouse, arresting Frazee just hours later.

Berreth, 29, was last seen at a supermarket in Woodland Park with her daughter before she dropped the girl off at Frazee’s ranch home on Thanksgiving Day.

There have been no reports on whether Berreth’s body or remains have been found. The arrest warrant is sealed, and no bail has been set in the case, according to The Denver Post.