A Dorchester man was held on $100,000 cash bail today following his arraignment on charges that he shot a one-time friend in the chest, killing him, during a fight at an MBTA station earlier this year, Suffolk County District Attorney Daniel F. Conley said.

Assistant District Attorney Holly Broadbent for the first time today said that NHU NGUYEN (D.O.B. 5/5/92) was once friends with 19-year-old Derek Matulina, the man he allegedly shot to death at Savin Hill station on May 7, but the two became involved in an ongoing dispute over money Nguyen believed Matulina owed him from a drug transaction.

Nguyen, charged with manslaughter for Matulina’s death, encountered the victim “purely by chance” outside the Red Line station that afternoon and again demanded the money, Broadbent said. Matulina responded by challenging him to a fistfight. For his part, Nguyen allegedly pulled a handgun from his waistband.
“A witness who was friendly with both men urged the defendant to walk away,” Broadbent said.
Nguyen and Matulina entered the station separately, Broadbent said. A short time later, Matulina approached Nguyen and struck him in the head with an object later found to be a padlock tied to a handkerchief. A friend of Nguyen interceded and physically placed himself between the two men, ending the altercation.

Nonetheless, Broadbent said, “video surveillance shows the defendant stepping back and firing one shot directly at the victim’s chest before fleeing the scene.”

Nguyen left the area in the aftermath of the shooting, shutting off his cell phone and Facebook account, Broadbent said.

Based on interviews by Boston Police and MBTA Transit Police and the review of surveillance imagery from the scene, prosecutors approved a warrant for his arrest on May 10. Members of the Boston Police Fugitive and Apprehension Unit located and arrested him on May 12 in Portland, Maine. In a post-Miranda interview, Broadbent said, he admitted to the shooting.

Nguyen was charged with murder and held without bail at his Dorchester District Court arraignment. Based on the facts and circumstances of the shooting, he was indicted for manslaughter and firearms offenses and Broadbent today recommended that he be eligible for bail. Clerk Magistrate Connie Wong granted that request.

Nguyen is represented by attorney Randy Gioia. He will return to court on Aug. 16.