The Marines told Matthew Pickett that it was wrong to smuggle machine guns and hand grenades from Iraq back home to Tennessee.
After he returned to Bradley County, federal agents explained laws regarding explosives and firearms to him during police training at Cleveland State Community College.
But he had brought two fully-automatic AK-47 assault rifles and an undisclosed number of grenades home from Iraq in 2005. After he was hired by the Bradley County sheriff's office on Aug. 16, 2007, he sold one of the rifles and stored the other in his patrol car, records show.
"This individual sat through that class," said Darryl Hill, resident agent in charge of the U.S. Bureau of Alcohol Tobacco, Firearms and Explosives office in Chattanooga. "Federal explosives and firearms laws were explained to him."
This month, Pickett was charged with a single count of smuggling, a federal crime. He has filed paperwork stating that he plans to plead guilty on Sept. 9. He faces a maximum penalty of 20 years in prison and a $250,000 fine.
Pickett is not in police custody and could not be reached for comment Wednesday.
Documents show the former Marine hid the weapons in a vehicle fuel tank before leaving Iraq in 2005. When the vehicle was brought to Camp Pendleton, Calif., Pickett removed them and brought them home to Bradley.
He joined the county sheriff's department two years later and, in the summer of 2009, sold one of the rifles to someone in Bradley County, records show.
During an investigation by the FBI and the Naval Criminal Investigative Service, Pickett "confessed to stealing and smuggling the weapons," according to documents.
As a result of the federal investigation, Bradley County Sheriff Tim Gobble fired Pickett, records show. Also based on the federal investigation, the sheriff accused Pickett of using anabolic steroids, holding illegal narcotics evidence in his patrol car for four months, falsifying official documents and keeping three seized driver's licenses at his home.
Pickett did not face any criminal charges for these actions.
Gregg L. Sullivan, acting U.S. District Attorney for the Eastern District of Tennessee, declined to comment on the case Wednesday.
Pickett's attorney, Mary Ellen Coleman also declined to comment.
It is hard to put a price on a fully-automatic AK-47 in the Chattanooga area, but such weapons can fetch "thousands of dollars" in larger cities where there is higher demand, Hill said.
Investigators recovered both AK-47s but court documents did not mention what happened to the grenades.