ORANGE PARK – The Clay County Sheriff’s Office and U.S. Postal Service worked together to put two men behind bars and uncover a massive drug trafficking ring.

Jason Terril Setzer, 46, of Jacksonville, was charged with conspiracy to traffic more than 2,000 grams of fentanyl. Trafficking fentanyl, possession of marijuana and a firearm by a convicted felon and trafficking methamphetamine and fentanyl, and Alvin J.J. Mercado, 37, of Fleming Island, was charged with conspiracy to traffic fentanyl and trafficking fentanyl on Sept. 11 after investigators got a tip the two received large quantities of drugs through the mail. The arrests came after the CCSO SWAT and Narcotics Unit raided two homes on Sept. 10 and seized 30 firearms, as well as a large cache of drugs.

“We’ve been working on it since late June, early July,” Clay County Sheriff Michelle Cook said. “We could have continued this investigation, but these guys were distributing so much. We had to pull them off the street because just in a couple of months they brought in enough fentanyl to kill four million people. And so we had to remove them as quickly as possible because they truly are a danger to society with that level of distribution.”

The arrests were part of a multi-agency, including federal, state and county agencies, investigation that started in June, Cook said. The case started with a traffic stop by the Florida Highway Patrol in Jacksonville and quickly grew in scope. The arrests were in conjunction with large seizures of cocaine, fentanyl and methamphetamine in both Jacksonville and Nassau County. Less than a week before Setzer and Mercado was taken into custody, the Jacksonville Sheriff’s Office confiscated more than three kilos of fentanyl, more than one kilo of cocaine and 6,000 pills containing fentanyl.

Florida Attorney General Ashley Moody joined sheriff’s office officials Wednesday afternoon to provide details of the investigation and arrests.

According to two lengthy arrest reports, Setzer and Mercado received fentanyl, methamphetamine and cocaine from an address in California. Packages were sent to Setzer on William Paca Street in Orange Park and to Mercado at houses on Eagle Cove Drive and River Breeze Drive on Fleming Island.

According to the arrest report, bricks of the drugs were “broken down and then distributed.”

The drugs were sent to various locations in Northeast Florida and cash was mailed back to the same address in California, Cook said.

On Aug. 5, deputies watched Mercado deliver a priority mail box to the Fleming Island post office. The return address wasn’t valid, the post office said, and the name on the box was Calvin Marco. Detectives detained the box and they got a warrant to open it after CCSO K-9 Ory alerted them of the likely presence of illegal drugs. To be sure, deputies placed five other “control” boxes with the package believed to contain drugs. On Aug. 8, the dog only picked OUT the package delivered by Mercado.

According to USPS records, an additional five packages were sent from a Jacksonville post office – one weighing 11.19 pounds – to the same California address.

Since the investigation started, CCSO investigators have taken 8.35 kilos of fentanyl, 1.36 kilos of cocaine, 2.38 kilos of methamphetamine and $183,000 from the enterprise operated by Setzer and Mercado.

According to the Drug Enforcement Agency, fentanyl is 100 times more potent than morphine, and it only takes two milligrams to kill a person. Cook said the amount of fentanyl distributed by Setzer and Mercado in the past four months was enough to kill everyone in an 18-county area of Northeast Florida.

On May 11, Cook said Aleksejs Kovilov was found dead of an overdose that included fentanyl. Michael Edgar Stanley, 39, was charged on Sept. 20 with manslaughter for selling him the drug a day earlier at a retail store on Fleming Island.

The cases aren’t related, Cook said.

Cook said there have been 261 reported overdoses in Clay County this year with 34 drug-related deaths and six suspected overdose deaths.

Both men were arrested in separate stops on Sept. 10 and they were charged a day later.

The investigation is ongoing in both Florida and California and Cook said more arrests are expected.

Setzer’s bond was set at $17.105 million, while Mercado’s bond was set at $10 million. Both are due to be in court on Oct. 17.