Senior officials at the Fulton County Jail called in the FBI last year and disclosed their suspicions that jailers were smuggling cellphones, cigarettes and drugs into the detention center.

The FBI quickly launched an undercover operation that on Tuesday netted its third conviction of corrupt jailers. Before a federal judge, former detention officer Akil Scott, 31, of Lithonia pleaded guilty to two counts of extortion and two counts of attempting to possess what he thought was cocaine and then give it to an inmate inside the jail.

“This sends a strong message that corrupt activity will not be tolerated at the Fulton County Jail,” Sheriff Ted Jackson said. “The Fulton County Sheriff’s Office is giving full cooperation to the FBI as agents continue their work.”

After FBI agents were given the names of suspects, an inmate cooperating with the probe gave Scott a phone number that he said belonged to his “outside drug connection,” Assistant U.S. Attorney Brent Alan Gray said during Tuesday’s hearing. The inmate told Scott it was up to him if he wanted to call and arrange a deal and smuggle the drugs, Gray said.

Scott made the phone call, but it wasn’t to a drug dealer. It was to an undercover FBI agent posing as one, Gray said.

On Aug. 11, 2010, Scott met the undercover agent at a Publix parking lot in Buckhead, where the agent gave Scott a balloon filled with what he said was 7 grams of cocaine. It really contained powdered drink mix, Gray said.

A month later, Scott consummated a similar deal outside a Waffle House, getting another balloon filled with drink mix, Gray said. On both occasions, Scott delivered the balloons to the cooperating inmate inside the jail and was given $650 by the undercover agent for doing so, federal authorities said. Scott is to be sentenced Feb. 16.

On Nov. 8, former Fulton deputy Marvie Trevino Dingle Jr., 34, of Lithonia pleaded guilty to extortion and drug charges. In October, former jailer Derick Deshun Frazier, 32, of Stockbridge pleaded guilty to one count of extortion for accepting $300 to smuggle cellphones into the jail.