A onetime drug dealer on Connecticut’s death row for ordering the killing of an 8-year-old witness to a shooting was convicted Friday of another murder. Russell Peeler Jr. was found guilty of murder and attempted murder in the 1998 slaying of Rudolph Sneed Jr., a rival drug dealer, at a Bridgeport barber shop. Peeler showed no emotion when the verdict was announced, the Connecticut Post reported. Peeler was condemned to die in 2007 for ordering the murders of Leroy ‘‘B.J.’’ Brown, 8, and his mother, Karen Clarke, who were found shot to death inside their Bridgeport home in 1999. Authorities said B.J. had witnessed an attempt by Peeler to kill Sneed in a 1997 drive-by shooting.