PORTLAND – The man accused of fatally attacking an elderly Portland man apparently followed the victim’s car in the mistaken belief that he was someone else before assaulting him in a parking lot, according to court documents released Tuesday.

Derek Soucy, 25, apparently mistook the victim for a woman whose home he had visited minutes earlier, but continued following the victim even after realizing his mistake, the document said.

The 88-year-old victim, John McCann, was attacked as he tried to go into the supermarket to buy items for his sick wife, police said.

Soucy, who is accused of kicking McCann beyond recognition, entered no plea during his initial court appearance on Tuesday.

Witnesses said Soucy called the retired teacher and school administrator “the devil,” pushed him down and kicked him until a retired firefighter intervened. McCann died of massive head trauma, according to a police affidavit.

The affidavit said that Soucy quit his job at Idexx Laboratories in Westbrook before driving to a friend’s home, where he frightened the occupants so badly that they dialed 911.

As he was driving away, Soucy spotted a car that he believed was being driven by the friend and started following it. He realized the driver was actually an elderly man and followed him into the Westgate Shaw’s supermarket parking lot and attacked him.

“As the old man got out of the car, Soucy said he tried to get in the man’s car. The man told Soucy that he had the wrong person,” Detective Don Krier wrote in the affidavit. “Soucy said that he tackled the man to the ground and that it was easy because of his old age. Soucy said that he intended on killing the man because he believed he was Satan and needed to save the world.”

Soucy said he began kicking McCann until he believed he was dead, according to the affidavit.

Soucy’s lawyer, Neale Duffett, waived his right to a have a bail hearing within five days. Soucy was to remain held without bail at the county jail.

Judge E. Paul Eggert granted a request that Soucy undergo a psychological evaluation, which could help resolve two issues – whether the defendant is competent to stand trial, and whether he can be held criminally responsible for his actions. Duffett has described the attack as a “psychotic episode.”

If a court finds that Soucy committed the killing, but did so because of mental illness, he could end up in a mental hospital rather than prison.

Meanwhile, the killing sparked outrage in Maine’s largest city, where there were no homicides recorded in 2000.

Some were critical of bystanders for not intervening earlier.

Brad Martin, who ultimately stopped the beating, said he heard shouting as he was loading groceries into his truck. As he drove away he saw Soucy kicking McCann in the face.

Martin placed himself between Soucy and McCann and Soucy just sat down until police arrived.

Soucy, a Warren native, served in the Navy before settling in Portland three years ago.

The case was continued to Feb. 23 for a bindover hearing. Evidence could be presented to the Cumberland County grand jury before then.