A 16-year veteran of the U.S. Postal Service pleaded guilty in federal court Thursday to knowingly delivering mail parcels containing heroin in exchange for a portion of the drugs.

Former Maui postal carrier Michael Trento pleaded guilty to conspiring to distribute and possessing with the intent to distribute approximately 1 kilogram of heroin in 2012-2014. He also pleaded guilty to accepting a bribe on at least one occasion to make the deliveries.

Trento faces prison terms of 10 years to life for the conspiracy and a maximum 15 years for the bribery at sentencing in November. He also faces fines of up to $10 million and $250,000.

He remains free on $25,000 bail until then.

A March 25 grand jury indictment charges Trento and former and current Maui residents Curtis Howard, Leonard Balgas and John Fleischauer with the conspiracy. The indictment also charges Howard and Fleischauer with money laundering and Howard with bribery.

Howard, Balgas and Fleischauer are scheduled to stand trial in September.

Trento told U.S. District Chief Judge Susan Oki Mollway, “They asked me to do a favor because I was a mailman. We were all friends from before.”

Assistant U.S. Attorney Beverly Wee Sameshima told Mollway that Howard mailed the heroin to Maui from Oregon, where he had moved. She said Fleischauer paid Howard for the heroin by depositing money in Howard’s Maui bank accounts. She said Howard then made cash withdrawals or wrote checks on the accounts.

Trento’s lawyer, Jefferson Willard, said Howard mailed the parcels to a vacant address on Trento’s route that Trento provided.

Sameshima said Trento received a gram of heroin for each delivery. Trento said, “Started out as a half-gram, then went to a gram.”

Based on Trento’s admission to authorities that he delivered two to three parcels per month, and on Howard’s admissions and bank records, the government estimates that Howard mailed more than 2 kilograms of heroin to Hawaii from Oregon over the three-year period. And based on a price of $100 per gram, Sameshima said, the government estimates Trento received approximately $14,000 worth of heroin over the same period.

The Postal Service says Trento worked out of the Lahaina Post Office as a mail carrier. He retired April 14, three weeks after he was indicted.