OMAHA, Neb. (AP) — Federal authorities have arrested a man after what officials say is was the largest seizure of the drug fentanyl ever in Nebraska.

Drug Enforcement Administration agents arrested 27-year-old Edgar Navarro-Aguirre on Wednesday after seizing about 33 pounds of the drug, which is an opioid up to 50 times more potent than heroin. Even tiny doses of the drug can be fatal.

The U.S. Attorney’s Office says Navarro-Aguirre was traveling on an Amtrak train and was waiting at the Omaha station when agents noticed a suspicious bag. After getting approval to search the bag, they found the fentanyl.

Navarro-Aguirre faces charges of possession with intent to distribute a substance containing fentanyl. His initial federal court appearance will be Friday afternoon.

It wasn’t clear if he has a lawyer who could discuss the matter.

The potential street value was estimated at around $15 million.