A man awaiting trial on charges he drove the shooter away from 2009 triple murder in Dorchester was charged Monday evening with possession of a gun loaded with hollow-point bullets, according to Boston Police and the Suffolk County District Attorney's office.

Nigel A. Nichols, 25, of Brockton, was one of several men sitting in front of a house on Osceola Street in Mattapan around 6:30 p.m., drinking out of red cups when officers on patrol came by, police say. According to police, the group scattered - but Nichols seemed to flee faster, so the officers began following him:

"As officers got closer to the group and the one individual, he started walking away faster with both hands with both hands tightly clutched to his midsection," police say. "The suspect took off in a full sprint as officers got close to him and showed indications of being an armed gunman. Officers pursued the suspect based on their prior knowledge of the suspect and the behavior displayed indicating possession of a firearm. The suspect was pursued through several streets and backyards until he was eventually stopped as he was attempting to scale a fence in someone’s back yard. There, the suspect was detained and a search conducted of the areas that he ran through. The search enabled officers to recover a loaded semi-automatic .45 caliber handgun."

According to the District Attorney's office, "when police and probation officers grabbed him, they asked him where the gun was. He responded, "I ain't telling you [anything]." Soon after finding the .45 caliber Taurus PT 1911 handgun in the rear of 126 Belnel Rd., they deployed a thermal imaging device which showed that it was significantly warmer than its surroundings - evidence that it had been carried and tossed very recently. Further examination revealed that it was loaded with eight rounds of ammunition, including five hollow-point bullets."

Nichols was out on bail following his indictment for his alleged role in the murders of Shacora Gaines, Chantal Palmer and Anthony Peoples at a party on Mt. Ida Road on March 29, 2009. Prosecutors charge that Keron Pierre shot the three to death, then jumped into a car driven by Nichols, who sped away.

Nichols was arraigned yesterday in West Roxbury District Court on the new charges of unlawful possession of a firearm, unlawful possession of ammunition, unlawfully carrying a loaded firearm, disturbing the peace, trespassing and resisting arrest. A judge set his bail at $100,000, but revoked his earlier bail on the murder-related charge.

After his indictment last year, Nichols's bail on the accomplice charge was originally set at $150,000, but a judge later lowered that, letting him walk, the DA's office says.