By Kim Palmer CLEVELAND (Reuters) – An Ohio man’s execution by an untested two-drug method that left him gasping for several minutes drew promises on Friday for a lawsuit by his family and renewed debate over capital punishment in the United States. Dennis McGuire, 53, who admitting raping and killing a pregnant woman, was executed Thursday with a sedative-painkiller combination never before used in the United States, where lethal injection is the preferred method of execution. The execution witnessed by reporters and McGuire’s adult children took about 25 minutes to complete, amid reports that he gasped for an unusually long 15 minutes while clenching his fists, and that his stomach churned up and down visibly. Typical executions end in death after about 10 minutes of sleep, said Richard Dieter, executive director of the Death Penalty Information Center, which tracks the use of capital punishment.