The Clarke County sheriff's department and East Mississippi Drug Task Force helped stop an alleged operation to smuggle drugs into the South Mississippi Correctional Institution at Leakesville.
Corrections officer Fernandez Cortez Denson is the latest arrest.
"It was found that, Rose Davis being the sister of (inmate) Ricky Davis, was shipping illegal drugs through the mail," said Clarke County Sheriff Todd Kemp. "Denson, the guard there, was extorting money from both Rose Davis and Ricky Davis in order for Ricky Davis to distribute illegal drugs in the penitentiary itself."
Denson was jailed in Clarke County and is on administrative leave without pay, pending a hearing.
Rose Davis, of Quitman, was charged with conspiracy to deliver marijuana into the prison at Leakesville. She has since posted bond.
Her brother, Ricky Davis, is serving time at Leakesville for robbery and aggravated assault from Clarke County. Other charges are pending.