The mysterious disappearance of Colorado woman Kelsey Berreth on Thanksgiving Day shocked and confused the 29-year-old's immediate family, who explained she's not the type of person who would just take off without a trace.

The search for the flight instructor — the mother of a 1-year-old girl — has intensified in recent weeks.

Investigators pleaded with Berreth's fiancé, Patrick Frazee, to sit down with them to further discuss what happened the day she vanished, as he was the "last person" to speak with her "face to face." On Dec. 21, Frazee was arrested in connection with the disappearance.

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Berreth was last seen at a supermarket with their daughter on Thanksgiving.

“She’s not the kind that runs off. This is completely out of character,” Berreth's mom, Cheryl, explained at a news conference on Dec. 10. "Our sole goal is to get Kelsey out in front of everyone. Like I said, she doesn’t run off and someone knows where she’s at.”

Here's a timeline of events that have happened since Berreth's disappearance.

Jan 3 - Idaho woman investigated

An Idaho woman, who has not yet been identified, is being investigated for potentially disposing of a cellphone belonging to Berreth, according to reports.

Jan. 1 - Fiancé hit with 5 felony counts

More than a week after his arrest, Frazee was formally charged with five felonies, including first-degree murder, first-degree felony murder and three counts of solicitation to commit first-degree murder, FOX31 Denver reports. Frazee tried to hire someone at least three times to kill Berreth between September and November, prosecutors claim.

Dec. 21 - Fiancé arrested

Frazee was arrested on Dec. 21, a sheriff's official confirmed. He was seen being taken into custody at his Woodland Park home.

KELSEY BERRETH DISAPPEARANCE: FIANCE OF COLORADO MOTHER MISSING SINCE THANKSGIVING ARRESTED

He was charged with first-degree murder, court documents show.

Dec. 15 - Completing property search, $25K reward

Police completed their search of Frazee's property in Florissant, Colorado, on Dec. 15, though they couldn't provide any details about any clues or information uncovered during that time as the "warrant was sealed," the Woodland Park Police Department said in a Dec. 17 news release.

They did, however, confirm they have "still not found" Berreth.

There were at least 75 people — who used a backhoe for assistance — who helped dig up Frazee's yard.

Again, police said the case remained their "top priority," noting there have still been no arrests in Berreth's disappearance.

Earlier that day, police revealed an anonymous donor offered a $25,000 reward for any information that leads to the location or safe return of Berreth.

Dec. 14 - Search warrant

Woodland Park Police Chief Miles De Young said on Dec.14 he wants Frazee to speak with investigators to discuss the disappearance of Berreth, showing up at his door that same day with a search warrant — which reportedly came as a surprise to the man.

The police chief declined to identify Frazee as a suspect or person of interest in the case but said they are considering every possibility.

“At this point, we are considering every possibility,” De Young said.

Frazee's attorney Jeremy Loew said his client was never asked to voluntarily allow investigators to search his home or property.

'We encourage law enforcement to take whatever steps it deems necessary to find Kelsey Berreth and to be able to exclude Patrick Frazee as a possible suspect in this missing person investigation," Loew said in a statement at the time.

Dec. 13 - Candlelight vigil

Community members met at a flagpole in Woodland Park to pray and light candles in honor of Berreth.

The Woodland Park Police Department encouraged people to attend to show "love and support" for Berreth and her family.

Berreth's mother, Cheryl, was in attendance and recalled the last moment she spent with her.

“We talked just Thanksgiving morning,” Cheryl said, according to CBS Dever. “No big Thanksgiving meal at her home or anything like that.”

Dec. 12 - Police reveal timeline of events leading up to Berreth's disappearance

With assistance from Berreth's mother, police were able to release a detailed timeline of Berreth's disappearance on Dec. 12. The department confirmed several interviews are being conducted in an effort to gain information regarding Berreth's whereabouts.

Here's a look at the timeline, according to the Woodland Park Police Department:

Nov. 22 - Berreth spoke with her mother via cell phone. Around noon that day, Berreth was seen walking into a Safeway grocery store. Later that afternoon, Berreth's fiancé said he saw her when he picked up their 1-year-old daughter Kaylee.

Nov. 25 - The last location her cell phone pinged from was in Gooding, Idaho, nearly 700 miles away from her home.

Dec. 2 - Berreth's mother called the police department, requesting a welfare check on Berreth at her home.

Dec. 4 - The Colorado Bureau of Investigation was requested to assist with the investigation.

Dec. 11 - New footage revealed

On Dec. 11, the Woodland Park Police Department released a 14-second clip of Berreth entering a Safeway grocery store in Woodland Park with her daughter at 12:27 p.m. on Nov. 22 — the last known footage of the Colorado mom alive before she vanished.

“Investigators have released that information [the surveillance video] as part of this Facebook post in hopes that it may lead to additional tips in this case,” police said.

The police department's video has been viewed more than 100,000 times since it was posted.

Dec. 2 - Reported missing

Berreth was reported missing by her mother 10 days after she was last seen and heard from.

All of Berreth’s belongings, aside from her purse, were still at her Woodland Park home after her disappearance. Her two cars remain in Colorado, puzzling investigators as they search for the 29-year-old.

Police released Berreth's photo the following day, on Dec. 3, asking for the public's help in finding Berreth.

"Berreth is a white female, 29 years old, approximately 5'3", 110 pounds with brown hair," they described the woman in a news release.

Fox News' Matt Richardson, Robert Gearty, Katherine Lam and The Associated Press contributed to this report.