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The parents of a missing Colorado woman said in an amended lawsuit against her fiancé that she was in the midst of a custody dispute over their 1-year-old daughter when she disappeared Thanksgiving Day.

The fiancé and father of the girl, Patrick Frazee, was arrested and charged Dec. 21 with Kelsey Berreth's murder. Prosecutors believe he either killed her or that she died during a robbery he may have committed.

A picture Kelsey Berreth at a vigil in Woodland Park, Colorado on Dec. 13, 2018. Kelsey Brunner / The Gazette via AP

According to Friday's refiled wrongful death suit, Frazee argued in a phone call to Berreth's mother more than a week after she disappeared that the missing woman "had 'issues' that would warrant Frazee 'getting full custody' of their baby."

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The amended complaint states that the two broke up on Thanksgiving and that Frazee told the mother, Cheryl-Lee Berreth, that he "had enough and wasn’t going to deal with things anymore."

During the breakup, the suit alleges, "Kelsey had asked Frazee for her things back, so he gave Kelsey her keys and her gun."

The filing says the suspect told Cheryl-Lee Berreth that his fiancé ran off as she had done before. He accused Kelsey Berreth of abandoning the baby by leaving her with him, according to the new allegations.

Cheryl-Lee Berreth reported her daughter missing Dec. 2. Frazee's attorney said previously that his client "will continue to cooperate with law enforcement and continue to parent the child he shares with Ms. Berreth."

NBC News was unable to track down his current public defender.

The couple was not living together. Frazee told police that Berreth dropped off their daughter on Thanksgiving, the last time he saw his fiancé.

Police have said they believe she's dead and her remains have not been found.