JACKSON, Miss. (AP) — Federal authorities on Thursday announced indictments against 20 people, including 14 current or former Mississippi Delta law enforcement officers, that allege the officers took bribes to provide safe passage to people they believed were drug traffickers.

The yearslong investigation swept across multiple counties in the Mississippi Delta region of Mississippi and Tennessee. Two Mississippi sheriffs, Washington County Sheriff Milton Gaston and Humphreys County Sheriff Bruce Williams, were among those arrested.

Some bribes were as large as $20,000 and $37,000, authorities said at a news conference.

“It’s just a monumental betrayal of public trust,” U.S. Attorney Clay Joyner said at a news conference.

The indictments say law enforcement officers provided armed escort services on multiple occasions to an FBI agent posing as a member of a Mexican drug cartel. The indictments allege the officers understood they were helping to transport 55 pounds of cocaine through Mississippi Delta counties and into Memphis. Some of the officers also provided escort services to protect the transportation of drug proceeds.

Gaston and Williams are alleged to have received bribes in exchange for giving the operations their “blessing,” one indictment said. It also alleged that Gaston attempted to disguise the payments as campaign contributions, but did not report them as required by law.

Federal officials said the investigation into the alleged crimes began when people who had been arrested complained about having to pay bribes to various individuals.