A Massachusetts man already in prison for paralyzing another man in a stabbing has pleaded guilty to manslaughter two years after the victim died.

Nicholas Cirignano entered his plea Tuesday in Norfolk Superior Court in the death of Matthew Nagle. Prosecutors had charged Cirignano with murder after Nagle's 2007 death was blamed on the stabbing. But Cirignano's attorney successfully argued for the lesser charge.

Cirignano stabbed Nagle at a Fourth of July celebration in 2001. He was sentenced to 10 years in prison after being convicted of assault with intent to kill and assault and battery with a dangerous weapon.

Norfolk District Attorney William Keating said Tuesday prosecutors discussed the case with the victim's family and agreed to a plea bargain that would give Cirignano 10 years' probation after his current sentence.