Murphy's Debt (en Inglés) - H Paul Doucette; Shipton

Matt receives a call from one of his regular clients, Lucy Hastings; a lawyer he has worked for several times in the past, asking for his help. Her nephew, Jack Forbes, has recently returned home from serving in the US Army in Vietnam. Unfortunately, he was involved in an incident resulting in his dishonourable discharge and a criminal record. Turns out, while over there, his squad was implicated in a set of murders which he witnessed and gave evidence against the killers. Now he was back home, trying to put his life back together. Then one day he spotted one of his old squad-mates; Willie Scaggs, the primary killer he helped to convict and send to prison in Leavenworth. He also remembered Scaggs' last words to him on the day he was sentenced to somehow see him dead. Matt agrees to look into the matter and determine if Scaggs was actually here and then report it to the proper authorities. However, a day after meeting with Forbes, he learns that the kid's body was found in an alley in the Village; he had been beaten to death. He realized he did not do more and if he had, maybe Forbes might still be alive. Now it was personal. 

Editorial Review of Murphy's Debt, by JD Shipton

Vietnam was at least peripherally responsible for delivering some unscrupulous characters on Canada's doorstep. When old debts get settled and bodies turn up, Matt Murphy finds himself in the middle of it. He'll have to call up old contacts and make some new ones to bring some kind of justice back to the streets of his hometown, but the grittier side of PI life ain't what it used to be.