The presence of blood on the toilet in Kelsey Berreth's bathroom -- first spotted by her mom -- led investigators to a slew of forensic evidence pointing to the 29-year-old Colorado mom's murder and unraveling her suspected killer's cover story, newly released search warrants reveal.

Authorities released the documents Wednesday showing the evidence that led to the December arrest of Patrick Frazee, Berreth's fiancé. Frazee was taken into custody a month after the 29-year-old woman was last seen alive, entering a Safeway supermarket with the couple’s 1-year-old daughter, Kaylee. Berreth, who is presumed dead, hasn’t been located.

When she was reported missing Dec. 2, authorities initially believed Berreth may have killed herself -- but the flight instructor’s mother, Cheryl Berreth, insisted her daughter’s disappearance was suspicious. She believed Frazee, 32, had been using Berreth’s cellphone to text her recently in an attempt to establish an alibi and said she was tipped off to the alleged ploy because her daughter never wrote in fragmented sentences.

Cheryl Berreth also discovered blood around the outer bowl of the toilet in her daughter's house in Woodland Park, Colo. She noted a bath mat that was in the bathroom in October was nowhere to be seen.

“Cheryl stated while looking for the rug/mat she noticed the refrigerator appeared to have been wiped down because she could see visible wipe marks on it,” a search warrant stated.

AUTHORITIES CALL 'WITCH IS DEAD' POST IN PATRICK FRAZEE CASE A 'STRANGE COINCIDENCE': REPORT

Investigators began searching Kelsey Berreth’s house and said they discovered several surfaces in the bathroom — including the ceiling, towel rack and doorknob — tested positive for Berreth’s blood.

Adding to her suspicion, Berreth’s mother recalled Frazee getting visibly upset the day his daughter was born. Cheryl Berreth said Frazee was “verbally abusive” toward the nursing staff because the parents were initially kept away from the newborn, who needed special medical care, leading one of the nurses to call social services.

“Cheryl stated Patrick later stated he should have ‘killed’ the nurse that reported them and then joked about the incident at [Kaylee's] first birthday,” the warrant stated.

Investigators later backed up Cheryl Berreth's other theory, reportedly concluding the text messages sent out from Berreth’s phone after Nov. 22 -- when she's believed to have been killed -- were written by Frazee and his girlfriend, 32-year-old Krystal Jean Lee Kenney. Cheryl Berreth said the last text message she received from her daughter on Nov. 24 read, “I’m tied up, I’ll call you later." She never got a call back.

Frazee, who was the last person to see Berreth alive, also had a bottle of bleach and a Swiffer mop that tested positive for blood in his possession.

Kenney initially told detectives she knew nothing about Berreth, but soon confessed to taking the Colorado mother’s phone to Idaho, where she disposed it.

She told investigators Frazee had been planning to kill the mother of his child since at least September 2018 and at one point approached her about carrying out the murder.

LANDFILL SEARCHED WHERE MISSING COLORADO MOM KELSEY BERRETH’S REMAINS ARE BELIEVED TO BE LOCATED

Kenney testified Frazee told her he beat Berreth with a bat and then asked Kenney to come to the house to clean up the blood. She recalled Frazee burning Berreth’s body and giving her the 29-year-old’s gun to “lead investigators to believe that Berreth might have committed suicide," the search warrant stated.

Police began searching Midway Landfill in Fountain, Colo., in late February in hopes of finding Berreth’s charred remains and “any additional evidence” linked to her death.

Kenney pleaded guilty to evidence tampering.

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Berreth’s parents filed a wrongful death lawsuit in which they claim Frazee killed their daughter as part of a custody battle.