LEWISTON - A woman was strangled in her apartment at 101 Birch St. and her son charged with murder Monday, police said.

Police said 47-year-old Debra Audet's sexual relationship with her son and daughter-in-law may have led to her death.

Investigators said the son, 22-year-old Matthew Audet, called them shortly before midnight Sunday to report that his mother had stopped breathing.

An autopsy Monday revealed that Debra Audet, who was suffering from cancer, had been choked to death. Her son was arrested after he was questioned by Lewiston and Maine State Police.

Police who went to the tall apartment house near the corner of Bartlett Street found Debra Audet dead inside the second floor apartment she shared with Matthew and his wife.

Matthew's wife, 19-year-old Kayla Stevens Audet, told police she had seen Matthew strangling his mother on a mattress on the floor.

"Kayla described Debra as lying on her back ... and her skin looking pale," according to an affidavit written by State Police Detective Jennifer King. "Kayla said Matthew was above Debra with either one or both hands on Debra's throat."

According to the affidavit, Kayla was preparing to leave Matthew, and the pair had argued about it earlier in the night. After she saw Matthew strangling his mother, Kayla tried to leave the apartment, she told police.

"While Kayla was in the bedroom gathering her things to leave, she said Matthew came up to her and said, 'I killed my mom, I killed my mom,'" according to the affidavit.

Police interviewed Matthew and Kayla Audet and someone who lives on nearby Bartlett Street. In the course of those conversations, they learned that Matthew had been having a sexual relationship with his mother dating back to when he was 8 or 9 years old, according the court document.

That person also told police that Debra had been having sex with Kayla, Matthew's wife, as well. Kayla later confirmed to police that she had been involved in a sexual relationship with her mother-in-law, according to the affidavit.

Police said the relationship between Kayla and Debra began when Matthew joined the Army, from which he was recently discharged.

Matthew had argued with his mother earlier in the day about her sexual behavior with his wife, according to the affidavit.

Police said Matthew told them he had been drinking with his mother on Sunday night at the apartment. They drank beer, Night Train wine and Mad Dog liquor. Matthew also said his mother began yelling at him, reminding her son that she had cancer and might die soon.

According to the affidavit, Matthew admitted going into his mother's bedroom around that time to "calm her down."

"Matthew said he held his right hand on her neck for approximately 30 seconds," police wrote in the affidavit. "Matthew then left his mother on the mattress in her room and went into the living room."

When he returned to the bedroom a short time later, Matthew told police, his mother was not breathing. He called police and initially told them his mother had choked herself.

At 101 Birch St., neighbors described a turbulent relationship between Kayla, Matthew and Debra Audet. Debra had recently been undergoing chemotherapy to treat cancer but had stopped in recent days, according to a woman who lived above them.

"I talked to her just yesterday. She said she wasn't on chemotherapy anymore, that she was feeling better," said 22-year-old Heather Hudson, who lives above the Audet apartment.

She said there were arguments from the apartment downstairs, but that she never saw indications that Matthew was mad at his mother.

"Every time I saw him with his mother, they were drunk and laughing and having a good time," Hudson said. "I didn't think that anything was going bad between them."

Other neighbors said the Audet apartment was often the scene of partying and that things often got loud there.

"You could always hear them yelling like crazy," said Tom Taylor, who stays with his girlfriend on an upper floor apartment. "They'd stay up until four o'clock in the morning and stuff like that."

The troubled relationship between Matthew and Debra Audet is documented in the courts, as well. Last May, sheriff's deputies went to a trailer they shared at 12 Poplar Drive in Poland after receiving a report that the mother and son were fighting. When they arrived, police found Matthew behind the wheel of a Saab and his mother standing nearby.

Debra had a cut on her forehead and her son was drunk with a knife hanging from a chain around his neck, according to court records.

At the time, Matthew was on leave from the military. He admitted that he drank a bottle of vodka with his mother and was later charged with driving while intoxicated after failing a sobriety test. His blood-alcohol level was later measured at .26, according to court records.

In subsequent days, police were called again to intervene on a dispute between the couple. Matthew Audet was charged with violating bail conditions at least once. In November, he was convicted of drunk driving while the violating charge was dropped.

It was believed Debra, Kayla and Matthew Audet left Poland for Lewiston when they were kicked out of their trailer. Neighbors guessed they had been living on Birch Street since November.

Court records reveal a minor criminal record for Debra Audet. In 1999, she was found guilty of filing a false public report and paid a $75 fine.

According to the affidavit, Matthew had been working sporadically on jobs assigned by Labor Ready. On his MySpace page, Matthew lists V.I.P as his place of employment. His only posted message on the page states: "I love Kayla." Kayla is also the only friend he has listed.

On Kayla's MySpace page, she describes herself as "in love with the man of my dreams." In a questionnaire asking if she has ever cheated, she responded: "Once."

Matthew Audet remained at the Androscoggin County Jail in Auburn Monday night. He was expected to make his initial court appearance Tuesday morning.