Complex sentence: The 50th convicted killer executed in Georgia since 1973 was Roy Willard Blankenship on June 23,2011; it was the first execution carried out using a new sedative, pentobarbital, in place of sodium thiopental.
Split into simpler sentences: The 50th convicted killer executed in Georgia, Roy Willard Blankenship on June 23,2011, since 1973 and was the first execution carried out with a new drug mixture. It was the state's first execution using a new sedative, pentobarbital, in place of sodium thiopental.