CONCORD, N.H. — New Hampshire Attorney General Michael Delaney said Friday that after a thorough review, he will not pursue a criminal investigation into the 2003 death of a Massachusetts boy, despite pleas from the family to reopen the case.

Delaney said there was insufficient evidence to pursue the case of Patric McCarthy, 10, of Cape Cod who was found dead in the White Mountains after he went missing during a family vacation.

State police, New Hampshire Fish and Game Department agents and federal investigators hiked the area last September “to assess the concerns that potentially the body had been dumped there,” Delaney said.

“Over the course of the past six months, I completed an independent review of the case file,” Delaney said. “There has been an extensive amount of follow-up, investigative work in this case, and I have reviewed all of that and do not believe that additional investigative steps are warranted at this time.”

The boy was reported missing while vacationing with his family in Lincoln over the Columbus Day weekend. His stepbrothers said he was racing them 300 yards back to the family’s condominium and got lost. He was found dead four days later after an extensive search.

An autopsy concluded Patric died of hypothermia. But his family has tried to get prosecutors to reopen the case as a homicide investigation.

Delaney said if additional, credible evidence were found, his office would conduct another review.

“I’m very disappointed,” said Deanne Murray, Patric’s mother, of Buzzards Bay, Mass. “My son was murdered. This was no accident.”

She said a private investigator assembled accounts from four pathologists who do not believe Patric died of hypothermia.

“This is not a hypothermia case,” she said. “His clothes were never found, hat was never found, his coat was never found. He had bruising on his gumline, he had dirt up his nose, he was straight out in a prone position, he had lesions on his face. I mean come on, it’s ridiculous.”

Patric’s body was found face down about 2 1/4 miles from the condo, in difficult terrain and about 1,400 feet higher than where he was last seen.