AUBURN – A Lewiston man charged with killing his mother pleaded guilty Tuesday to manslaughter.

Matthew Audet, 23, of 101 Birch St. told a judge in Androscoggin County Superior Court he believed prosecutors could have proved his guilt beyond a reasonable doubt had the case gone to trial.

Justice Joyce Wheeler told Audet she could impose any sentence up to 30 years in prison for the Class A crime, plus probation for up to six years.

“Yes, your honor,” he said. “I’m aware of that.”

Audet also could be fined up to $50,000, though the state’s attorney said she likely wouldn’t be seeking a fine. A sentencing hearing was set for Jan. 13 when the defense attorney and the prosecutor are expected to argue their respective recommendations for length of prison time and probation.

Audet signed a document waiving his right to have the state present his case to a grand jury for indictment.

He has been held in Androscoggin County Jail without bail since his arrest in March, his once-bleached hair now a natural dark brown.

Justice Wheeler told Audet he would be giving up his right to trial and to appeal his conviction or sentence with his plea, though he could still petition for a review of his sentence.

“I plead guilty, your honor,” he said.

Assistant Attorney General Lisa Marchese detailed the case for the judge, touching on evidence and testimony that would have been presented at trial.

Police responded to a 911 call Audet made saying his mother might have tried to commit suicide by choking herself.

His wife, Kayla, would have testified that Audet and his mother, Debra, were watching TV that night while drinking heavily in the apartment shared by the three of them, Marchese said.

Kayla told police she was packing because she was leaving Audet. She said she saw Audet who appeared to be choking his mother as she was lying on a mattress on her bedroom floor. Debra Audet was lying on her back, her tongue hanging out of her mouth. Her skin was pale.

He later came into her room and told her: “I killed my mom.” He asked her to help him think of a lie, Kayla said.

Kayla would tell the jury that her husband had abused his mother over the years, including one time when he broke her wrist. He would hit and kick her and had tried to choke her before.

Marchese said she wouldn’t get into details of the sexual relationship Audet reportedly had with his mother, starting when he was a child. A friend told police both Audet and his wife had a sexual relationship with Debra Audet. Marchese said she would elaborate at the sentencing hearing.

An autopsy revealed manner of death consistent with strangulation, Marchese said. Debra Audet’s blood-alcohol level was 0.31 percent, nearly four times the legal driving limit, Marchese said.

Justin Leary, Audet’s attorney, said he and his client agreed with Marchese on the “essential facts” of the case.