Long, 55, promised to inform them when he became aware of any investigation focused on their involvement in illegal activities, including selling ingredients used to make methamphetamine, the court record said.
Then the FBI set up a sting, introducing "the sheriff to what he believed was a money laundering and drug trafficking operation," the affidavit said.
The affidavit said Long also accepted $6,550 in cash as "his payoff to a cooperating witness supposedly laundering $625,000 in drug trafficking proceeds."
Long was given $1,000 by the confidential informant, money provided by the FBI, and told that drug trafficking money "would be hidden in the cremation urns to a funeral home in Mexico."
A judge ordered Long detained after federal prosecutor Gary Humble described Long as a "danger to the community." Long told U.S. Magistrate Bill Carter that he would hire a lawyer before a Monday afternoon detention hearing.
Long, a Democrat, was elected in 2006 after 31 years of law enforcement service.
"Law enforcement corruption cannot be tolerated and must be dealt with quickly and professionally," U.S. Attorney James R. Dedrick said in a statement.
Dedrick said no other law enforcement officer was a suspect in the investigation, which he said is ongoing and could lead to additional charges. Dedrick declined to say if anyone outside of law enforcement is a suspect.