BARRIE, Ont.

It was on the eve of a Satanic holiday when Mark Dobson, lost in the heady art of witchcraft, nearly decapitated two women with a utility knife in a bloody murder-suicide pact, a Barrie courtroom heard Monday.

Dobson, 24, pleaded not guilty to two counts of first-degree murder. His lawyer wants the court to find him not criminally responsible for the deaths of his girlfriend, Mary Hepburn, 32, of Barrie, and their friend, Helen Dorrington, 52, of Cold Lake, Alta.

The women were found with their heads partially severed, their bloodied bodies surrounded with tiny blood-crusted dolls in a room at the Travelodge motel on May 2, 2012, court heard.

Police allegedly found Dobson standing at the door naked and bleeding, mumbling to police that they were all going to live gloriously on another planet.

The Crown contends that while Dobson suffers from mental illness, he understood his actions were morally and legally wrong.

“All three believed in the demon world,” Crown attorney Shannon Curry said in her opening statement.

The killing was allegedly a celebration of Beltane — a Satanic holiday which has been associated with human sacrifice.

As a child, Dobson would often tell his mom there were aliens in the room and by the age of 14, he studied witchcraft and Satanism, court heard.

“His friends were interested in girls, but he was interested in magic,” said Curry.

At 17, he became a Wiccan and met Hepburn and Dorrington on a Satanic chat line called The Joy of Satan.

Dobson and Hepburn fell in love and moved to Barrie, where they lived together in squalor.

Eventually the three made a suicide pact and Dorrington travelled to Barrie, court heard. They rented a room at the Travelodge, partied, ate takeout food, and the women took some crushed pills to calm down.

Dobson allegedly told them to lie down and he began to strangle them, as planned.

“Mary said ‘No’ and began to struggle ... She was scared,” Curry said. “He twisted her neck and he heard a snap, but she was still breathing ... So he got a knife and he began cutting her neck, but she was still saying ‘no.’”

Even as Hepburn lay “gurgling,” Dobson stuck his fingers in her throat so he wouldn’t have to hear her last pleas, court heard.

Dobson went to where Dorrington lay on the second bed, groggy from the pills, and went to work cutting her throat quickly before dawn ended.

“Later he admitted what he had done. He said he knew it was wrong and he knew he would go to jail,” Curry said.

On the witness stand, one of the first officers on scene described the horrific scene with the bloodied bodies of the two women on the beds, their throats so deeply cut their heads were almost off.

“To me it looked like they had been decapitated,” Barrie Police Const. Andrew Butler testified. “It was a grisly scene ... It was gruesome.”

The trial continues.