ABC News has confirmed that Patrick Frazee, the fiancé of missing Woodland Park mom Kelsey Berreth, was taken into custody at his home in Teller County Friday morning, and authorities say they don't believe she is alive.
Frazee was being held at the Teller County Jail.
Frazee has been booked on a charge of first-degree murder and solicitation of first-degree murder, but officials explained it may be about 10 days before he is formally charged, according to Dan May, attorney general for Colorado's 4th Judicial District.
Authorities also declined to elaborate on the solicitation of murder charge, how they believe Berreth was killed or any other aspect of the investigation. One of the last places she was seen was at a Safeway in Woodland Park, shopping with her daughter.
Surveillance video showed Berreth entering the store with what appeared to be her 1-year-old daughter in a baby carrier. "But they've dealt with that and they've made things work regardless", she said.
Police said the only signs of Berreth were some text messages from her cellphone.
Police said that a search of Berreth's home on Thursday night turned up "suspicious" items and brought them to a point where they could arrest Frazee.
Police later received data indicating Berreth's phone was near Gooding, Idaho that same day, almost 800 miles (1,300 kilometres) from her home. Frazee had told police that the couple met that afternoon so he could pick up the child.
"He is communicating with us through his attorney", De Young said. "That's the last time Kelsey was seen", he said. Data indicated Berreth's phone was near Gooding, Idaho, at the time the texts were sent. "This is completely out of character".
She was reported missing December 2. She was reported missing earlier this month by her mother, who lives in Idaho.
Family and friends started a Facebook page to spread and gather further information on her whereabouts.
Police arrested Patrick Frazee Friday morning at his home in the community of Florissant, Colorado. "She's reliable, considerate, and honest".
A text from her phone to her employer, sent on November 25, said that she would not be coming into work that week.
Frazee voluntarily released his phone to be searched and allowed officers to take a DNA sample on December 12, his lawyer said. Investigators were working to recover it.
Frazee runs a cattle ranch, and prices for the industry have been poor, delaying their plans to find a house and move in together, Cheryl Berreth said.
Authorities said as many as 30 FBI agents are participating in the investigation in several states.