The fiancé of 29-year-old mother Kelsey Berreth, who was last seen in Woodland Park on Thanksgiving, has been formally charged with first-degree murder in relation to her disappearance.

Patrick Frazee was arrested Friday, Dec. 22, nearly one month after Berreth was last seen on surveillance footage at a Safeway. 

That was Nov. 22, Thanksgiving Day. 

Below is a timeline of events and 9NEWS coverage on the case of the missing Colorado mom. (Note: Events are listed in reverse chronological order.)

Feb. 26: Investigators begin searching landfill for Kelsey Berreth’s remains

Investigators arrived at a landfill south of Colorado Springs Tuesday morning to start their search for the remains of Berreth. 

RELATED: Investigators begin searching landfill for Kelsey Berreth’s remains

Feb. 22: Law enforcement to search landfill for Kelsey Berreth’s remains

Woodland Park Police detectives and other law enforcement officials announce they will start searching a landfill in Fountain next week for the remains of Berreth.

RELATED: Law enforcement to search landfill for Kelsey Berreth’s remains

Feb. 20: Cell phone records, video provide timeline of Kelsey Berreth killing

Cell phone records and security camera footage paint a timeline of when investigators believe Frazee beat his fiance to death with a baseball bat, according to an arrest affidavit from the Woodland Park Police Department.

RELATED: Cell phone records, video provide timeline of Kelsey Berreth killing

Feb. 19: CBI: Idaho nurse claimed Patrick Frazee fatally beat Kelsey Berreth, burned her body

A CBI agent testified in court that Idaho nurse Krystal Kenney Lee told him that she helped Frazee clean up a “horrific” crime scene after she said he murdered Berreth.

CBI Agent Gregg Slater, who testified during Frazee's preliminary hearing in Teller County court, recounted details that investigators say confirm Berreth was murdered.

In addition to first-degree murder and solicitation to commit first-degree murder, prosecutors added counts for tampering with a deceased human body and crime of violence, which is a sentence enhancer.  

The judge ruled there is enough evidence for Frazee to stand trial for the charges against him.

He is slated to be arraigned April 8.

RELATED: CBI: Idaho nurse claimed Patrick Frazee fatally beat Kelsey Berreth, burned her body

Feb. 15: Family: Custody of 1-year-old daughter was Patrick Frazee's motive in Kelsey Berreth murder 

Kelsey Berreth's parents say they believe her fiancé Patrick Frazee killed her because he wanted full custody of their 1-year-old daughter.

That's according to an amended wrongful death lawsuit the 29-year-old's family filed against Frazee on Friday. In the lawsuit, it's alleged that Frazee and Berreth actually broke up on Thanksgiving Day and that Berreth agreed to share their young daughter 50/50, which he did not want. 

RELATED: Family: Custody of 1-year-old daughter was Patrick Frazee's motive in Kelsey Berreth murder

Feb. 8: 'I learned that Patrick Frazee had committed a homicide': Idaho nurse pleads guilty to moving Kelsey Berreth's cell phone

Krystal Kenney, 32, appeared in Teller County Court, where she pleaded guilty to a felony for tampering with physical evidence. She also read a statement where she said she learned Frazee "committed a homicide on approximately Nov. 22, 2018 in Teller County."

RELATED: 'I learned that Patrick Frazee had committed a homicide': Idaho nurse pleads guilty to moving Kelsey Berreth's cell phone

Feb. 7: Daughter of Patrick Frazee, Kelsey Berreth to remain in custody of maternal grandparents

A Teller County Court judge ruled that Frazee's and Berreth's 1-year-old child will remain in the custody of her maternal grandparents.

RELATED: Daughter of Patrick Frazee, Kelsey Berreth to remain in custody of maternal grandparents

Feb. 4: Idaho nurse investigated in disappearance of Kelsey Berreth faces one count of tampering with evidence

Krystal Kenney, 32,  faces one count of tampering with physical evidence, a class 6 felony, according to a complaint filed in Teller County Court. Her appearance is scheduled for Friday, Feb. 8.

RELATED: Idaho nurse investigated in disappearance of Kelsey Berreth faces one count of tampering with evidence

Jan. 5: Berreth’s parents file wrongful death lawsuit against Frazee

The lawsuit was filed on behalf of Darrell and Cheryl-Lee Berreth in U.S. District Court for the District of Colorado. It seeks unspecified damages against Frazee.

RELATED: Kelsey Berreth’s parents file wrongful death lawsuit against her fiancé, Patrick Frazee

Jan. 4: Frazee allowed to see arrest affidavit in the case against him

Jennifer Viehman, the district attorney assigned to the case, said she would allow Frazee's attorney to review the arrest warrant affidavit, but asked that he not share it or discuss it with Frazee. In the hearing, it was determined that Frazee could now access the arrest affidavit in the case against him.

RELATED: Patrick Frazee allowed to see arrest affidavit in the case against him

Jan. 4: Idaho nurse being investigated for disposing of Berreth's phone, NBC News confirms

Details about the woman and how she is connected to the Berreth case are limited at this time, but it has been confirmed to NBC that she is a 32-year old nurse from Twin Falls, Idaho. That's about 35 miles from Gooding, Idaho, where investigators previously said Berreth's phone pinged on Nov. 25.  

RELATED: Idaho nurse being investigated for possibly disposing of Kelsey Berreth’s cell phone

Jan. 3: 1-year-old daughter to stay in custody of Berreth's grandparents

The courts rule that the daughter of Berreth and Frazee will continue to remain in the custody of the maternal grandparents and child protective services. This was the second hearing on the matter.

RELATED: 1-year-old daughter of Kelsey Berreth, Patrick Frazee to stay in temporary custody of Berreth's parents

Dec. 31: Frazee charged with five counts related to Berreth's disappearance

Frazee appeared in Teller County court on Monday, Dec. 31, where he was formally charged with two counts of first-degree murder and three counts of solicitation to commit first-degree murder. 

RELATED: Kelsey Berreth’s fiancé charged with five counts, including first-degree murder

Dec. 27: Courts rule that Berreth's and Frazee's 1-year-old daughter will remain in custody of maternal grandparents

Teller County court ruled that Kelsey Berreth's parents will retain physical custody of the child and that the Teller County Department of Human Services will retain legal custody. Frazee's mother has since filed a motion to intervene in the decision.

RELATED: Daughter of Kelsey Berreth, Patrick Frazee to remain with maternal grandparents

Dec. 24: Court documents detailing elements of the legal proceedings against Frazee released.

The documents included a request from Frazee’s public defenders asking that investigators turn over emails and text messages they’ve recovered. 

RELATED: New documents released in case against Kelsey Berreth’s fiancé

Dec. 22: Twin Falls, Idaho police announce they assisted the FBI and the Colorado Bureau of Investigation with the case.

Police in Idaho worked with the FBI and CBI to serve several search warrants and process evidence as part of the ongoing investigation into the missing Colorado mom. 

RELATED: FBI reached out to Twin Falls police to process evidence related to Kelsey Berreth's disappearance

Dec. 21: Frazee arrested for first-degree murder and solicitation to commit first-degree murder

Patrick Frazee was taken into custody just after 7 a.m. Friday and is expected to face charges of first-degree murder and solicitation for first-degree murder. 

RELATED: Kelsey Berreth’s fiancé arrested for murder, solicitation for murder

Dec. 18: Law enforcement returns to Frazee's home

Police officers and agents with the Colorado Bureau of Investigation were seen going in and out of Frazee's home Thursday night.

RELATED: Law enforcement returns to Kelsey Berreth's home

Dec. 16: Search of Frazee's home concludes; Berreth not found

Investigators said Berreth remains missing after detectives executed a search warrant at her fiancé's 35-acre property over the weekend. 

RELATED: Search of Kelsey Berreth's fiance's property concludes without finding missing mom

Dec. 15: $25,000 reward offered for Berreth's return

Woodland Park Police announce a $25,000 reward for information leading to Berreth's safe return.

RELATED: $25,000 reward offered for information leading to missing Woodland Park mother

Dec. 14: Police search the home of Frazee

Law enforcement agencies first appeared at Frazee's 35-acre Florissant property to execute a search.

RELATED: Missing Colorado mom: fiance's home, property searched; Reward offered

Dec. 12: Frazee issues statement saying he's cooperating

Through his attorney, Frazee said he voluntarily released his phone to law enforcement for a search and provided buccal swabs and photographs.

RELATED: Fiancé of Kelsey Berreth, missing Colorado mom, issues statement saying he's cooperating

Dec. 12: Mom talks about the relationship between her Kelsey Berreth and her fiancé 

Cheryl Berreth, the mother of Kelsey Berreth, told NBC News that it's not like her daughter to go missing, and that Kelsey Berreth and Patrick Frazee we "loving," and that the relationship hasn't been ideal given the economy ... but that "they've made things work regardless."

Dec. 10: Mom pleads for the safe return of her daughter

Kelsey Berreth's mom, Cheryl Berreth, spoke at a news conference on Monday, Nov. 10, where she pleaded for the safe return of her daughter.

RELATED: 'Someone knows where she is:' Mother missing out of Woodland Park since Thanksgiving

Dec. 7: Officials release information about Kelsey Berreth's phone pinging in Idaho

Kelsey Berreth's phone pinged in Gooding, a small southern Idaho community. Police said the ping happened sometime on Nov. 25.

RELATED: Phone of missing Colorado mother pinged in Idaho

Nov.-22-Dec. 2: Kelsey Berreth last seen; mother reports her missing

Kelsey Berreth's mom first reported her daughter missing on Dec. 2. Investigators said she was last seen in surveillance footage at a Safeway with her daughter on Nov. 22, Thanksgiving Day.