When police rushed to Dudley Street, where someone had been shot on a May afternoon, they found Peter Carvalho leaning over the dying man.
Carvalho was sobbing, said his lawyer, mourning the victim, Shannon Richardson, 25, who had been his best friend since they were teenagers.
Police arrested Carvalho that day, believing that he had stalked, then shot his friend for reasons that initially bewildered them. The May 21 killing troubled many nearby residents, including those who knew the two friends and questioned whether police had arrested the right man.
But on Monday, Suffolk prosecutors presented a new theory of the killing: Carvalho accidentally shot Richardson while he was trying to kill someone else.
“It appears that Peter Carvalho may have hit Shannon Richardson with friendly fire as he was aiming at another target,” Assistant District Attorney Tara Burdman said Monday in Suffolk Superior Court, where Carvalho was arraigned on charges of first-degree murder and unlawful firearm possession.
Carvalho, 25, pleaded not guilty to the charges as he stood behind a courtroom door. His lawyer, Kelli Porges, had asked that Carvalho be allowed to remain outside the courtroom to protect him from potential false eyewitness identification.
Porges said Carvalho and Richardson had been friends since they were 15 years old and described the case against Carvalho as “very thin.”
“There is no murder weapon,” Porges said. “No motive . . . . This is certainly a very sad day for both families.”
Porges successfully argued to have the statement of the case — a document that lays out the investigators’s allegations of the crime — impounded, which kept Burdman, the prosecutor, from going into specific details about the police investigation of the killing.
Burdman was able to say that Richardson, Carvalho, and a third man were together the afternoon of May 21, just before 1:30 p.m. in a vacant lot on
the corner of Dudley and Humphreys streets.
Burdman did not say who Carvalho was allegedly aiming at when he fired, but two law enforcement officials with knowledge of the investigation said the shooting was connected to a gang conflict. Carvalho has ties to a Dorchester gang with a long history of retaliatory shootings, one of the officials said.
According to a police report, as police were heading to Dudley Street in response to the shooting, two gang unit officers driving down Dudley Street saw Carvalho and the third man, identified in police reports as John Archer, emerge from a pathway, jogging. Those officers followed Carvalho and Archer, who ran toward a store on Dudley Street, where Richardson had staggered after he was shot in the neck and torso.
A witness said a man resembling Carvalho had shot Richardson, fled, then came back to the crime scene.
But Porges said her review of the police investigation found contradictory witnesses, who pointed to another man as the shooter. She said that Carvalho spoke with officers when they arrived.
Burdman countered that a grand jury investigation into the killing helped prosecutors develop strong evidence against Carvalho, including testimony from reliable witnesses who have no ties to either the victim or the suspect.
Relatives for both men were in court Monday, but declined to comment after the hearing.
Following the killing, neighbors were besieged by gunfire on Wendover Street, close to the site of the slaying. No one was struck, but many wondered whether it was connected to Richardson’s killing. Neighbors began meeting regularly and reactivated a neighborhood crime watch, said state Representative Evandro Carvalho, a Dorchester Democrat who is not related to Peter Carvalho.
Some of those neighbors also openly challenged the department’s theory that Peter Carvalho was the killer, he said.
“So many people were saying no, it can’t be him because they’re best friends,” said Evandro Carvalho, who worked briefly as a Suffolk prosecutor. “From the beginning, neighbors, friends and family were in disbelief.”
He said he hoped the new theory would help people feel more confident about the department’s investigation.
“That’s what the neighborhood needs,” he said, “a way to rebuild trust with the police and the judicial system. This hopefully can bring some peace of mind.”