A 64-year-old mother and her 43-year-old son face serious jail time after the son's wife saw them having sex.

Tony Lavoie and his mother, Cheryl Lavoie, from Fitchburg, Massachusetts, could face 20 years behind bars if convicted.

Lori, Tony's wife, relayed her suspicions to authorities after finding her husband and his mother having sex in the living room.

On her Facebook page, Lori indicated that she has separated from her husband - even though all three of them were living under the same roof.

After calling cops, she said she 'always had suspicions of the two of them having an intimate relationship.'

Detailing what she had seen, Lori said that 'she saw her mother-in-law naked on top of her husband.'

Due to shock, she said nothing to either party and instead went into her room and shut the door.

She then called her cousin Joan before calling the cops.

Following the arrest, the mother and son said that having sex was consensual.

And when cops asked Tony what had happened, he said:

"I don't want to talk about it. I made a mistake. It embarrasses me enough to think about what I did."

He also confirmed that he and his biological mother 'did have sex.'

He said:

"It just happened."

And when officers asked him how, Tony added:

"I don't know, it just happened."

He then said that he played a video game in the living room when he kissed his mother.

He also admitted he had sexual intercourse with his mother, saying they 'took off each other's clothes.'

Also, Tony insisted that was his first time he did something like that.

The officers, however, said Tony 'wasn't nervous or upset for having sex' with his mother. He was more troubled that his wife saw it.

Cheryl's story was also similar to that of her son, according to the police report.

She said that her son's wife caught them having sex and that she was 'on top of [him], on the couch.'

Cheryl also agreed with her son's account that the encounter had been consensual. She added that it was her first time to have sex with the son.

When officers asked if her son has any mental illness, she said she didn't know.

In the arraignment, the two pleaded not guilty to felony incest.

The court then ordered them to stay away from each other upon release on their own recognizance — waiting for a pretrial hearing.