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An ex-convict was ordered held without bail Tuesday as a prosecutor described how he allegedly fatally shot four people — including a 2-year-old boy and his mother — during a drug robbery in Boston.

In a courtroom packed with friends and relatives of the victims, not guilty pleas were entered for Dwayne Moore, 33, on charges of murder, armed robbery and home invasion.

Moore, who prosecutors said was released from prison earlier this year after serving a 10-15 year sentence for manslaughter, did not appear in the courtroom. He stood behind a door that was slightly open so he could hear the charges, but he was not visible to most people in the courtroom.

Moore's court-appointed lawyer, John Amabile, said his client "vehemently denies" any involvement in the slayings.

Killed in the Sept. 28 shootings were 2-year-old Amani Smith; his mother, 21-year-old Eyanna Flonory; her boyfriend, 21-year-old Simba Martin; and 22-year-old Levaughn Washum-Garrison. A fifth victim, 32-year-old Marcus Hurd, was critically wounded.

Assistant Suffolk District Attorney Edmond Zabin said Moore and Martin knew each other from prison, where they had served time together. Martin let Moore stay with him after he was released from prison last summer at his apartment in the city's Mattapan neighborhood, where Moore knew Martin kept "a supply of drugs and cash," Zabin said.

Moore and Kimani Washington, 34, went to Martin's apartment late on the night of Sept. 28 to rob him, the prosecutor said. While they were trying to get Martin to come outside, Hurd arrived. When Martin came outside to meet Hurd, Washington and Moore forced the two men inside and made them strip off their clothing, Zabin said.

After Moore went through the apartment and took cash, drugs, a TV and other items, the five victims were "marched up the street ... where they were shot multiple times," the prosecutor said.

Washington was charged earlier in the investigation with weapons violations, receiving a stolen car, drug trafficking and being a career criminal. He pleaded not guilty and his lawyer has said he "unequivocally denies" hurting anyone.

Zabin offered no precise details about Moore's and Washington's alleged roles in the shootings. Prosecutors said earlier that one of the guns used in the slayings was found during a search of the apartment of Washington's mother.

A witness who testified before a Suffolk County grand jury identified Moore "as having used a firearm while he was an active participant in the home invasion and robbery," according to court records.

Police arrested Moore on Monday after interviewing him. When police told Moore he would be charged with murder, he said: "I can't do this, I can't go back to jail, you're going to have to kill me," according to a description included in court records.

Moore's lawyer did not contest the prosecution's request that his client be held without bail.

Amani Smith's grandmother, Inez Smith, said she was relieved by Moore's arrest.

"I am happy they caught the killer," she said. "I know Amani is watching down from heaven right now."

The shooting was the single deadliest in Boston since December 2005, when four young men were fatally shot in a makeshift basement recording studio in the Dorchester neighborhood. Two men are serving prison sentences for that shooting.

Moore is due back in Dorchester District Court on Dec. 22.