Oklahoma has executed John David Duty, 58, on Thursday keeping alive its capital punishment policy. The difference this time was that it used for the first time a drug called pentobarbital, a sedative that is used as euthanasia for animals.

Apart from pentobarbital, Department of Corrections spokesman Jerry Massie told Reuters that two more drugs were used in a drug cocktail, which has replaced sodium thiopental, a sedative that was in short supply. The use of the new drug to execute convicts was approved by a federal court.

Duty was convicted for killing his cellmate Curtis Wise after strangling him with a bedsheet. This year saw three executions in Oklahoma and the 46th in the United States.Oklahoma also became the first American state to use pentobarbital in executions.

Duty was the 94th person to be executed in Oklahoma since 1976 and third this year. The other two persons executed earlier this year include Julius Ricardo Young on Jan. 14, and Donald Ray Wackerly II on Oct. 14.