A Norristown teenager who used an illegal gun to kill a man during a robbery was sentenced Friday to 50 to 100 years in state prison.

Damon Brantley Jr., 18, was convicted of first-degree murder in September for the killing of William Carter, 35, during a robbery planned in January by another man, Daquan Allen.

Allen, 30, and another accomplice, Jerry Butler, 29, were convicted of second-degree murder and serving life sentences. Carter’s ex-girlfriend, Katherine Emel, had tipped Allen off about Carter’s whereabouts as part of a plan to steal money he had recently won from sports gambling.

The three men, along with 17-year-old Justin Davis, cornered Carter on Wood Street on January 20. During the scuffle, Carter also fought back Brantley shot him three times in the head with a gun modified into an automatic weapon, killing him instantly.

At the time of the shooting, Carter was outside the home where the mother of his child lived with their then-1-year-old daughter.

After the shooting, Brantley wrecked the stolen car the four men were driving in the robbery and fled the area before being arrested in upstate New York by US Marshals.

During Friday’s hearing, Assistant District Attorney Meghan Carney asked Montgomery County Circuit Court Judge William Carpenter for a lengthy sentence, saying Brantley has shown no remorse for his actions. He forced prosecutors to bring the case to trial despite a mountain of evidence proving his involvement, including testimony from Emel and Davis, she said.

“I keep using the word ambush because that’s what it was: (Carter) was unarmed, he was just walking to his car when … he was approached by three grown men, tackled and then executed,” Carney said. “Running for his life when he was shot.”

But Brantley’s attorney, Evan Kelly, said his client was a good person who had been left to fend for himself by his family, had no permanent home and was sleeping on friends’ floors and couches.

“He’s a good kid who got involved in a horrible situation and it became a tragic, horrible mistake,” Kelly said. “My heart goes out to the family and what happened to them.”

Kelly described Brantley as “very redeemable.” He said the murder was a “robbery gone wrong” and that Brantley had no intention of killing Carter.

Carney disagreed, saying Brantley made a series of conscious, deliberate actions that led to Carter being shot in the head on a cold Norristown street.

She also pointed out that Brantley was a week away from turning 18 on Jan. 20, an age at which a murder conviction would mean an automatic life sentence, like those given to his two co-defendants. his, who were adults at the time of the shooting.

Carpenter, the judge, agreed with Carney and called Brantley dangerous as he handed down the lengthy sentence.

Kelly said he plans to appeal the judge’s decision.