BOSTON – The co-defendant in a Lynn man’s murder trial has pleaded guilty in Suffolk Superior Court to taking part in the May 31, 2008 stabbing death of 24-year-old Curtis Ashford.Roberto Mendes, 20, of Jamaica Plain, pleaded guilty to manslaughter Wednesday, receiving a prison sentence of up to 20 years rather than face trial.Earlier this month, Edward Holloman, 21, of Lynn, pleaded guilty to second-degree murder in the same court and was sentenced to life imprisonment.Holloman fatally stabbed Ashford, a Roxbury resident, following a late-night altercation on East 8th Street in South Boston. He was arrested for first-degree murder shortly thereafter and has been behind bars ever since awaiting trial. Holloman agreed to the reduced charge, making him eligible for parole after 15 years.Had Mendez faced trial, Assistant District Attorney Mark Hallal was set to introduce evidence and testimony to prove the defendant and others were socializing at a friend’s house in South Boston when the crime occurred. The resident of that home went out onto his front steps, where he became engaged in a verbal argument with someone on the street. The two men exchanged heated words. Ashford arrived and became entangled in the argument.According to Jake Wark, spokesman for District Attorney Daniel Conley, evidence would have shown the three men and the resident of the home squared off against Ashford and two companions. When Ashford attempted to walk away, the three defendants followed. Ashford tried to take cover inside another home, but was unable to get past the locked door.Ashford and one of the defendants began fist fighting. Mendes handed Holloman a knife and told him to stab Ashford.Holloman allegedly stabbed Ashford multiple times in the chest and abdomen. The three assailants fled, tossing the knife in a sewer. Darren Hemingway, 20, of Brighton, drove Holloman and Mendes from the murder scene. Ashford died at Boston Medical Center.Prior to sentencing, Ashford’s sister, Lenise Young, told the court, “My brother was no saint, but he was a good person. He was loved by so many people and never hurt anyone. He was a father and a friend to man and you took that away from us.”Young said her brother has a two-and-a-half year old son. “You can’t possibly ever understand what it feels like to look at that baby every day and see his father in him, knowing he will never get to know Curtis as we did. When he is old enough, what do we tell him about his father’s death? That he was killed by cowards?”Hemingway was also indicted in the case as an accessory after the fact.