FRANKFORT, Ky. – The U.S. Drug Enforcement Administration has taken supplies of a key lethal-injection drug from Kentucky and Tennessee, effectively preventing any executions in three states while it investigates how the drug was imported during a national shortage.

States have been scrambling over the past year to find a new supplier of sodium thiopental, a fast-acting sedative in a three-drug cocktail used when putting inmates to death, since its primary manufacturer in the United States stopped making the drug.

In March, the DEA took Georgia’s entire supply, putting a hold on executions there following claims from a defense attorney for a death row inmate that the state bought the drug from a fly-by-night outfit in the United Kingdom.

Kentucky officials confirmed Friday that they turned their supply over to the DEA, and Tennessee officials said that they relinquished theirs March 22.

There are currently no scheduled executions in Kentucky because of a court order that has temporarily halted them. In Tennessee, four inmates are scheduled for execution in September and October of this year.

The DEA and state officials have given few details about the investigation except to say there were questions about whether the drug was imported properly.

Kentucky officials said they were cooperating in an unspecified federal investigation and the state willingly turned over its entire supply — enough for three executions.

“There was no court order and no search warrant,” said Jennifer Brislin, spokeswoman for the Kentucky Justice Cabinet. She declined to comment further.