The request from public defender David Barron comes about a month after a Georgia death row inmate's attorney asked for a similar investigation. Justice Department officials didn't immediately return telephone calls Tuesday, but previously the agency has said they were reviewing the request.
Drug Enforcement Administration officials said about a week ago they had seized Georgia's supply of the drug.
A national shortage of sodium thiopental has prompted many states to look overseas for it. Sodium thiopental is a sedative used in many executions to start the lethal injection process.