Although Judge Jeffrey Locke described the sentence he was about to hand down as “lenient,” he agreed to the request of prosecutors and a defense attorney to sentence a Dorchester man to two and a half years in jail for fatally shooting a teen last year.

Nhu Nguyen, 20, pleaded guilty yesterday to charges including manslaughter during a plea hearing at Suffolk Superior Court. Nguyen admitted to fatally shooting his friend, 19-year-old Derek Matulina, during a fight at the Savin Hill MBTA station last May.

Matulina’s father Robert said that he wanted to see Nguyen serve a longer sentence.

“This is the best we could do,” Robert Matulina said. “It’s a tough pill to swallow.”

Deirdre Murphy, Matulina’s mother, gave a tearful impact statement during the hearing.

“The court has allowed you to plead guilty to manslaughter and walk away from murder,” she said. “But you know and I know murder is what happened on that Savin Hill platform.”

If the case went to trial, prosecutors would have to prove that Nguyen used excessive force for self-defense. Assistant District Attorney Holly Broadbent said the recommended sentence takes into account that Nguyen had no adult convictions and his age.

“It’s lenient,” said Locke, “but it does seem to fully factor in all of the facts and circumstances surrounding this event.”

Nguyen and Matulina were friends who would sell marijuana together, Broadbent said.

The two crossed paths at the T station last May and an argument broke out over a debt from a transaction. Matulina tried to get Nguyen to fight him, but Nguyen refused and flashed a gun. While walking toward the station platform, Nguyen turned his back and that’s when Matulina repeatedly hit him in the head and back with a padlock tied to a bandanna.

Nguyen had nowhere to run, with Matulina’s friends blocking the station’s exit and electrified tracks on either side of the platform, lawyers for both sides said.

That’s when he shot Matulina once in the chest.

Police found Nguyen at his father’s house in Maine days after the shooting.