A Stoughton man who fatally shot a rival through a window as the victim lay in bed has been convicted of second-degree murder. Michael Blanchard was convicted Tuesday in Norfolk Superior Court of killing Stephen Erving, 21, at about 3:30 a.m. March 16, 2010. Prosecutors said Blanchard, 24, fired several rounds from a 9mm pistol through Erving’s first-floor bedroom window. Authorities said the men knew each other and had a long-running feud. Blanchard’s lawyer has said that Erving had previously threatened his client.