Ohio carried out its first execution in more than three years Wednesday morning when it put to death Ronald Ray Phillips, 43, a convicted child murderer, using a new, controversial three-drug cocktail. The mix of midazolam, a sedative-hypnotic, rocuronium bromide, a paralytic agent that inhibits breathing, and potassium chloride, an electrolyte solution that prevents the heart from beating, had been challenged by Phillips and other death-row inmates who say it causes an agonizing death.