PORTLAND – A judge on Thursday accepted a plea agreement that will send Derek Soucy to Augusta Mental Health Institute for the savage beating death of an elderly man outside a Portland supermarket six months ago.

Superior Court Justice Paul Fritzsche accepted the agreement that Soucy, 25, was insane at the time of the attack and not criminally responsible for the murder of John McCann. Soucy beat the 88-year-old retired school administrator to death in the parking lot of Shaw’s supermarket at Westgate Shopping Plaza in view of a group of stunned onlookers.

Lisa Marchese, the prosecutor in the case, said the state had no choice but to accept the plea agreement because there was no way to overcome the evidence. “It was a clear case of paranoid schizophrenia,” she said. “At the time Derek Soucy committed this crime he was suffering from delusions that Mr. McCann was the devil.”

The brutality and randomness of the Jan. 12 attack on McCann shocked the community. Soucy, a Navy veteran with no history of violence or mental illness, attacked McCann in broad daylight with no provocation.

When police arrived, they found McCann in a pool of blood with Soucy nearby. He later told them that he recognized McCann as Satan while driving behind him on Congress Street and followed him into the supermarket parking lot.

In videotape played at Thursday’s hearing, Soucy admitted his guilt to investigators. When asked why he attacked McCann, Soucy replied: “To kill the devil and save the world.”

After the hearing, Soucy’s father, Greg Soucy, said he was “heartbroken” for the McCann family and the anguish the incident had caused.

“I never met John McCann, but I know he was a loving, decent man,” he said.

The plea was agreed upon earlier this month by the state because the psychological evidence was so overwhelming. The McCann family reluctantly agreed it was the best course to accept.

Soucy is scheduled to be sent to AMHI Friday for an indefinite period of time. It will be up to doctors and the court to determine if and when he is ever released.