An inmate at Boston’s South Bay House of Correction was found dead in his cell early Saturday afternoon, according to a spokesman for Suffolk County Sheriff Steven W. Tompkins. Rohan Blackwood, 28, of Boston, was found unresponsive by a corrections officer conducting rounds at about 12:16 p.m., said Peter Van Delft, the sheriff’s spokesman. Van Delft said the guard issued an emergency alert and attempted CPR, but was unable to revive him. Blackwood, who was imprisoned on a conviction for assault with a deadly weapon, was pronounced dead at the scene, Van Delft said. A preliminary investigation found no sign of foul play or suicide, Van Delft said, but Boston police and the sheriff’s department are continuing to investigate.

Correction: An earlier version of this story gave the wrong timeframe in the death of an inmate at the South Bay House of Correction.