Police responding to a call for gunshots Saturday in residential Mansfield arrived to find a Manchester-by-the-Sea man in the street, armed and clad in body armor, with another man dead from multiple gunshot wounds to his head, prosecutors say.
“On May 20, 2022, at approximately 11:11 a.m. there was a 911 call from the town of Mansfield, 42 West Church Street, in which a male caller reported a male at that location suffering from a gunshot wound to the head,” said prosecutor Patrick Driscoll. “Police arrived on the scene a short time period later and found a man, allegedly the defendant, in the street with body armor on him.”
The defendant William O’Brien, 22, of Manchester-by-the-Sea, was arrested after the fatal shooting of 23-year-old Samuel Waters, of Mansfield, on Saturday. He was first charged on two firearm counts and then, on Monday morning, with one count of murder.
O’Brien attempted to flee the scene, Driscoll said, but was apprehended by police a short time later carrying a firearm.
Waters was dead went police arrived, according to the Bristol County DA’s Office. A medical examiner determined the cause of death to be multiple gunshot wounds to the head.
The defendant allegedly told officers, “I apologize for killing Samuel,” among others statements suggesting he’d killed someone, Driscoll said. Witnesses at the scene also allegedly identified O’Brien as the killer.
O’Brien was on probation for prior firearm convictions, Driscoll said, leading to the initial firearm charges against him after he was found allegedly illegally carrying the weapons Saturday.
Police also found large quantities of marijuana and cash at the scene of the shooting, the prosecutor detailed.
“Your honor, Mr. O’Brien is 22 years old,” defense attorney Neil Madden said to the judge Monday. “And as you can surmise from the Commonwealth’s case, there was a lot more going on in that house.”
Madden said the defense would “reserve initial arguments” to get a better understanding of the case.
The judge ruled O’Brien will be held without bail.
Several of the victim Samuel Waters friends attended the arraignment, audibly crying through the proceedings. Summer St. Hilaire, who said she went to Nichols College with Waters, said she didn’t know if or how he knew his alleged killer.
“He was my best friend,” St. Hilaire said outside the courthouse. “I loved him.”
Massachusetts State Police, Homicide Unit prosecutors and Mansfield Police are continuing to investigate the homicide, the DA’s office said. Police in water gear could be seen scouring the Rumford river near the house.
The case will continue in Attleboro District Court on June 22.
