The Supreme Court on Monday ordered a new trial for a Pennsylvania death row inmate in a 17-year-old murder case, ruling that his attorney was sloppy in failing to investigate possible evidence of mental retardation.

In a 5-4 decision, justices ruled in favor of Ronald Rompilla, 56, who was convicted of robbing, stabbing and setting on fire a tavern owner in 1988. It was the second time in a week that the high court overturned a death row sentence, citing an inadequate trial.