PORTLAND, Ore. — U.S. prosecutors said Monday they have charged an Oregon drug smuggler in what they described as a sordid murder-for-hire plot that targeted an associate who owed tens of thousands of dollars for marijuana trafficking services.

Authorities say John Tobe Larson, 68, offered an informant $20,000 to kill the associate, whom he had met in prison, and dump his body at sea so it would never be found.

He paid the informant $10,000 from money he had made on a marijuana smuggling run to St. Louis and promised the other half — but only if there were pictures showing the victim’s body being dumped at sea, court papers filed in U.S. District Court in Medford state.

Larson told the informant that disposing of the body in the open ocean would ensure ”‘lice and crabs’ would naturally eat away at and dispose of the body, and ‘the teeth are in sediments at the bottom of the ocean,’” according to the criminal complaint.

“I have been in this business for over fifty years, this is not my first rodeo,” Larson told the informant, who was wearing a concealed recording device, the documents state.

Larson of Josephine County made hs first court appearance on Monday, the same day a complaint filed against him more than a month ago was unsealed.

He did not enter a plea and was ordered held without bail. His public defender, Clayton Lance, did not respond to a phone message or email on Monday.

Based on a tip from the informant, Larson had been under investigation since May for illegally trafficking bulk marijuana from Oregon around the U.S. using a private plane and smuggling cash back into the state, records show.

Shortly after the investigation began into that activity, Larson approached the informant about the hit job, documents say.

Marijuana is legal under Oregon law but remains an illegal and controlled substance under U.S. law. It is illegal to transport it across state lines.

Josephine County, where Larson was arrested, is part of an area of southern Oregon and northern California nicknamed the Emerald Triangle for its ideal climate for growing high-quality cannabis.

Since legalization in Oregon, many growers have started state-legal businesses, but authorities say illegal diversion remains a big problem and growers and sellers not registered with the state continue to operate in the shadows.

U.S. authorities in Oregon have, for the most part, ignored cannabis operations that follow state law but have made a point of going after illegal operations that ship Oregon marijuana across state lines.