Convicted killer William Rousan was executed early Wednesday morning and pronounced dead at 12:10 a.m.
Rousan received the death penalty for orchestrating the 1993 farm slaying that claimed the lives of Grace and Charles Lewis at their farm just outside Bonne Terre.
Attorney's for Rousan had filed a request for clemency over concerns about the state's lethal injection drugs a day after an Oklahoma court stopped two executions there over similar issues. Gov Jay Nixon declined the clemency request late Tuesday evening, clearing the way for Wednesday morning's execution.
This is Missouri's sixth execution since last November.