Callers posing as a Rutherford County Sheriff's Office lieutenant may actually be inmates from a South Georgia prison, a sheriff's supervisor said Friday.

A man identifying himself as Lt. Michael Blackman with the Sheriff's Office recently called a woman and told her she missed jury duty and a warrant was issued for her arrest, said Detective Lt. Todd Sparks. She could avoid arrest by providing green dot money packs in the amounts of $1,000 and $95.61.

The caller stayed on the line until she bought the green dot money backs and gave him the 16-digit pin numbers on the cards. They money was withdrawn. Another individual filed a similar complaint with Murfreesboro Police but realized the call was a scam.

Sheriff Robert Arnold said the Sheriff's Office employees never ask residents for cash to avoid arrest. Lt. Blackman does not work at the agency.

"We want residents who receive such calls to get the number if possible, hang up and call the Sheriff's Office immediately at 898-7770," Sheriff Arnold said.

Through his investigation, Lt. Sparks learned the phone was pre-paid with no subscriber information. He learned the caller made several hundred calls over a two-day period, making it appear the calls originated from the Sheriff's Office and Adams Place.

Working with other law enforcement agencies, Lt. Sparks and Detective Steve Craig learned the calls were placed by the inmates in the southern Georgia prison with calls made to Tennessee, Georgia and Texas.

Federal and local law enforcement agencies are investigating.