A Boston teenager was arraigned Monday in a Suffolk Superior courtroom for last October’s murder of an Adams Corner man and a subsequent double-shooting near St. Mark’s that left one man with multiple gunshot wounds.

John Graham, 17, pled not guilty to all nine charges— including first-degree murder in the Oct. 10 shooting death of 36 year-old Ciaran Conneely— and will likely stand trial for the crimes next year.

The small courtroom in Suffolk Superior Court was packed with onlookers, including relatives and friends of Conneely and the father of the defendant Graham. But the accused murderer himself was held just out of view of the courtroom, within earshot of Clerk Magistrate Gary Wilson, who presided at the arraignment. Police and prosecutors have also withheld photographs of Graham to date to preserve a fair trial, according to Wilson.

The suspect, who was 16 at the time these crimes were committed, will be tried as an adult as mandated by state law. Graham does not have a permanent legal address and had been living sporadically at the homes of relatives, including at least one who lives near the scenes of these two crimes.

Ian Polumbaum, the Assistant District Attorney who spoke for the prosecution, said that ballistic evidence, surveillance video footage and statements Graham allegedly made to others led to his arrest and subsequent indictment on Dec. 20. When Boston Police compared the ballistics evidence in the Oct. 10 and Oct. 30 shootings—they found that the same gun had been used at both scenes, Polumbaum said.

Graham is alleged to have shot Conneely during a robbery attempt near the corner of Adams Street and Nahant Avenue on the night of Oct. 9-10.

“Neighbors reported hearing a loud ‘bang’ after shortly after midnight,” said Polumbaum. Conneely was found a few yards from his Nahant Avenue apartment building shortly after 1 a.m. by a neighbor. He died later that morning from a single gunshot wound to the chest.

Prosecutors say that Graham “made statements to others” that he had shot Conneely in the chest near Adams Street while trying to rob him. But the real break in the case came when Graham was identified as the alleged shooter in the attack on Monsignor Lydon Way. In that incident, more than two weeks after Conneely’s murder, two men — ages 18 and 20— were accosted by a young man near the corner of Lydon Way and Dorchester Ave. on the night of Oct. 30. Police said that Graham produced a gun and demanded their money, but opened fire when the two young men did not cooperate.

“They thought the weapon was fake and refused,” Polumbaum said. “The defendant opened fire, striking one victim four times from behind and the other victim in the arm. The first victim suffered life-threatening injuries.”

Boston Police detectives were led to Graham, in part, by video surveillance in the area of the Lydon Street attack. The investigation led to Graham and “other persons aware of his involvement” in the crimes, Polumbaum said.

Graham was charged with first-degree murder, armed assault with intent to rob and unlawful possession of a firearm in the Oct. 10 Nahant Ave. murder. He was also charged with two counts of armed assault with intent to rob, an additional count of unlawful possession of a firearm, armed assault with an intent to murder, assault and battery with a dangerous weapon and aggravated assault with a dangerous weapon, for the Oct. 30 double shooting.

Graham’s attorney, Randy Gioia, asked that the two incidents be arraigned separately and the indictments relating to the Oct. 30 incident be deferred. But Wilson denied the motion, agreeing with Polumbaum, who argued that there was a credible connection between the two incidents.

Graham will be held without bail. The presumed trial date has been set for January 7, 2013, with a final pre-trial hearing on December 4, 2012. Graham is due back in court for a pretrial hearing on March 6.