BRIDGEPORT, Conn. (AP) — Authorities say a Connecticut man who was caught selling heroin mixed with carfentanil, an extremely powerful synthetic opioid sometimes used to sedate elephants, is the state's first federal prosecution involving the deadly substance.

The U.S. Attorney's office says Charles Thelusma was arrested last week and charged with possession with intent to distribute, and distribution of, heroin, carfentanil (kahr-FEHN'-tuh-nihl), and U47700, which is a synthetic opioid about seven times stronger than morphine.

Court documents say police coordinated two controlled purchases of heroin from Thelusma earlier this year. Authorities say a lab analysis of drugs purchased May 24 confirmed the presence of heroin, carfentanil and U47700.

Carfentanil is 100 times stronger than fentanyl and 10,000 times more powerful than morphine.

It couldn't be determined Sunday if Thelusma has an attorney.