Jack Callahan, 22, is currently on trial for allegedly drowning his father in a Massachusetts pond in June 2021 in an attempted exorcism, as he believed his father was possessed by a demon.

Callahan told police that he had submerged his father's head underwater in an effort to rid him of a demon called 'Dirty Dan.'

"I left him there to decide; you can come to heaven with me or hell. I think he chose hell," he told officers.

Scott Callahan, 57, a successful banker at the time, was receiving treatment for alcohol addiction at a facility in Hopkinton before he checked himself out and traveled to a bar in Boston.

The younger Callahan had traveled in an Uber to collect him and return him to the family home in Duxbury when he asked the driver to pull over for him to smoke a cigarette when they were near the pond.

The son claims his father then attacked him, punching him repeatedly.

At Callahan's 2021 arraignment, Assistant District Attorney Shanan Buckingham revealed,

"He went on to state that, in this incident at the pond, he believed he was baptizing his father."

"He described that he was holding his father in the pond on his back like a baby, that he continually dunked the father's head in the water about four to eight times, and that when the father started to cough and choke, he would lift his head up," Buckingham added.

He continued to do so until his father was no longer struggling.

The son was distraught when speaking to paramedics and explained that he had "blacked out" before directing police to Crooker Memorial Park, where they discovered Scott Callahan in the pond, according to The Independent.

Jack Callahan has denied the murder of the fifty-seven-year-old and pleaded not guilty to the charges.

Callahan's attorney, Kevin Reddington, previously asked the judge to send the then-teenager to a hospital for a mental health evaluation, warning that he posed a risk to himself.

The trial is expected to last 10 days.