(CRIPPLE CREEK, Colo.) — A Colorado man accused of killing his fiancée in a vicious assault in her home is now on trial for her murder, and the prosecution, which has already called the defendant’s brother to the stand, is still expected to bring its star witness: the accused’s ex-girlfriend, who claims she was called to help clean up the alleged murder scene.Kesley Berreth, who had a 1-year-old girl with her fiancé, Patrick Frazee, vanished on Nov. 22, 2018, which was Thanksgiving Day. The 29-year-old’s body has never been found.Frazee was arrested in December. Accused of charges including first-degree murder, he began facing trial last week. His ex-girlfriend, Krystal (Lee) Kenney, has pleaded guilty to one count of tampering with physical evidence and is awaiting sentencing once Frazee’s case concludes.Prosecutors allege the attack unfolded on Thanksgiving at Berreth’s Woodland Park, Colo., home as the couple’s baby sat in a playpen in a back bedroom.Frazee allegedly blindfolded Berreth and had her guess the scents of different candles, according to an arrest affidavit. While Berreth was distracted, Frazee allegedly hit her with a bat, which ultimately killed her, the document said.Kenney, who has not yet been called to testify, has claimed Frazee summoned her to clean up Berreth’s home after the alleged crime.She has also claimed Frazee had three plots for killing Berreth, including one that involved Frazee asking her to poison Berreth’s favorite Starbucks drink, a caramel macchiato, an investigator testified. Kenney claimed she and Frazee discussed potential drugs that were easy to access because Kenney was a nurse, an investigator said.Frazee’s older brother, Sean Frazee, who is a Colorado Springs police officer, testified Tuesday that the family sat down for Thanksgiving dinner at 3 p.m.Patrick Frazee did not show up until 5 p.m. and had his and Berreth’s baby with him, Sean Frazee said on the stand. Investigators believe Patrick Frazee had already killed Berreth by the time he arrived at dinner. Prosecutors argued in opening statements that Frazee was mentally abusing Berreth and wanted custody of their child. They presented a theory that when Berreth talked about possibly moving, Frazee panicked and enlisted the help of a former girlfriend to kill her.But the defense tried to cast doubt, arguing in opening statements that Frazee’s clothes weren’t bloody and he did not have injuries on his body.The defense has also pointed out that the victim’s body and the murder weapon have never been found.Berreth’s supervisor, Raymond Siebring, testified Monday for the prosecution that he received a text from the young mom’s phone the night of Thanksgiving. This text did not have an exclamation point or a smiley face, which was unusual for messages from Berreth, Siebring testified.Days later, on Nov. 25, Siebring said he received a text from Berreth’s phone to say she would be out of work the next week to see her grandmother. Siebring described that as unusual and said Berreth had never asked for a week off over text.David Felis, a Verizon store employee, testified Monday that Patrick Frazee came into the store on Dec. 4 asking questions about security of phone accounts and how information could be retrieved. Felis described Frazee as “extremely frustrated and upset.”Copyright © 2019, ABC Audio. All rights reserved.