COLUMBUS, Ohio (AP) — A drug used to sedate elephants and other large animals that is 100 times as potent as the fentanyl (FEHN’-tuh-nihl) already escalating the country’s heroin troubles is suspected in spates of overdoses in several states.

Authorities say they’ve found carfentanil (kahr-FEHN’-tuh-nihl) mixed with or passed off as much weaker heroin.

A central Ohio man suspected of selling carfentanil as heroin was indicted this week on charges including murder in connection with 10 overdoses, including one death. Investigators are still trying to track down the source.

Carfentanil also has been suspected in overdoses or found in Akron and Cincinnati, central Kentucky and western Florida.

A coroner in Cincinnati warned that the overdose antidote naloxone might not be enough to save people overdosing on carfentanil.