AUBURN – A teenager who attacked a man with an ice chopper two days before turning 18 was sentenced Thursday to serve more than three years in prison after he pleaded guilty to a charge of elevated aggravated assault.

Luke Blair of Lewiston said he was sorry for his involvement as one of a group of teens who robbed a man in an alley near Bartlett and Walnut streets about a year ago.

Before the sentencing in Androscoggin County Superior Court, a prosecutor described the attack and reviewed the evidence and testimony she would have presented had the case gone to trial.

Gary St. Hilaire was found lying on the ground in a pool of blood, his pockets turned inside out, when police officers arrived at the scene in November 2007. An ice chopper was found with St. Hilaire’s blood on the blade, its wooden handle splintered from the force of the blow.

The doctor who performed emergency surgery on St. Hilaire’s 9-inch-long skull fracture induced a coma for several weeks to allow St. Hilaire’s brain to recover. His language and memory are impaired, along with the right side of his body, Assistant District Attorney Melanie Portas said.

A witness would have testified to seeing Blair hit St. Hilaire on the back of the head with the ice chopper. Blair reportedly said he wanted to knock out St. Hilaire.

Richard Charest, Blair’s attorney, said his client agreed with the major facts of the case as described by Portas. She had dismissed a charge of attempted murder a week earlier.

Both sides agreed to a 12-year cap on his sentence. Prosecutors were seeking to have him serve five years; the defense, one year. He already has spent about five months in jail.

Portas said a psychological evaluation revealed Blair suffers from antisocial personality disorder and is someone who “operates according to his own rules and values.” She said he lacked remorse and empathy.

Blair apologized in court for his part in the robbery and assault.

“I accept the fact that what happened there was our fault,” he said. “His life is messed up because of something we did.”

But Blair pinned part of the blame for the attack on St. Hilaire because he allegedly was in the area to sell drugs.

In court, St. Hilaire read from prepared remarks, noting his doctor told him his head wound looked as though it had been caused by a machete.

“I hope this will stop you from doing this to another innocent person,” he said. Because of his injury, St. Hilaire walks with a limp and uses a cane to get around.

Justice Donald Marden asked Blair whether he was willing to “burn his bridges” and not consort with the same group of friends he was with the day of the assault. Blair said he would. He was working on his General Education Development certificate, he said.

“The defendant is a very, very young man,” Marden said, noting Blair turned 18 in June. Marden said he was concerned a long sentence with the adult inmate population could turn Blair into someone who is beyond rehabilitation.

“If he’s in there too long, he’s going to take on the characteristics of hardened prisoners,” Charest said.

Marden agreed.

“There is a great danger in the prospect of institutionalization,” Marden said. “The defendant needs help and he needs serious help.”

When he is released, Blair must provide for his 7-month-old daughter and pay $15,000 in restitution to St. Hilaire. If other members of the group that attacked St. Hilaire are convicted, they would share in that responsibility, Marden said.