Allen Nicklasson was scheduled to be executed Oct. 23, but concerns over the drug that was to be used has led Missouri Gov. Jay Nixon to halt the lethal injection, the AP reports. The convicted killer was to be the first person in the US to be put to death using propofol, the anesthetic that figured in Michael Jackson's death. The European Union, which provides almost 90% of the propofol used in the US, threatened to limit exports of the drug if it was used in executions. Nixon ordered the state's Department of Corrections to come up with an alternate method of lethal injection.