Brotherly love can make a man do strange things. On the night of Oct. 23, 1989, Matthew Stuart pulled his car alongside a blue Toyota parked in a predominantly black Boston neighborhood. The driver of the Toyota, Matthew's brother Charles, handed him a purse through the window. Accompanied by his friend John McMahon, Matthew ditched the purse in the Pines River. It contained the engagement ring of Carol Stuart -- as well as the .38 revolver that Charles had just used to kill his pregnant wife and then wound himself.
The murder transfixed the nation and aggravated Boston's racial tensions after...