One of the South Carolina inmates who federal authorities say posed as a young women on dating apps, and collectively extorted hundreds of thousands of dollars from service members, was sentenced to nearly four years in federal prison.

Jimmy Dunbar, 37, of Bishopville, who is serving a 30-year sentence at Lee Correctional Institution for murder, kidnapping and armed robbery, will serve 46 months in federal custody following his current sentence, according to the U.S. Attorney's Office for South Carolina. Dunbar was found guilty on federal charges of extortion, money laundering and conspiracy to commit wire fraud. He could have been sentenced up to 20 years.

Dunbar posed as multiple young women on a dating site and exchanged messages with government employees, authorities said. Those who were targeted belonged to every branch of the military, except the Coast Guard.

After Dunbar would send the service members nude photographs he found online, he would request them in return. Then the inmate would call the service members posing as a furious father. The young woman they were exchanging nude photos with, he would tell them, was a juvenile — not an 18- or 19-year-old, as claimed on the app, authorities said.

Dunbar would then threaten to report them for being in possession of child pornography unless they paid up large sums of money via wire transfers, prosecutors said.

Between September 2016 and January 2017, Dunbar personally received $29,598 in hush money from at least 17 people.

Federal investigators in August said five South Carolina inmates and nine others across the state, plus one in Charlotte, were charged in connection to what they dubbed a "sextortion ring."

Two women, both 29, pleaded guilty Wednesday to federal charges associated with the scheme, the U.S. Attorney's Office said.

Andreika Mouzon of Kingstree pleaded guilty to conspiracy to commit wire fraud and money laundering, prosecutors said. Flossie Brockington of Columbia pleaded guilty to money laundering.

Evidence shows that Mouzon and Brockington acted as "money mules," receiving extorted money via wire transfer, then sending the money to inmates and associates, prosecutors said.

"During the course of the conspiracy, Mouzon was responsible for transferring $20,421.73 of extorted funds from at least 11 service members, and Brockington was responsible for transferring $14,465 of extorted funds from at least eight service members," prosecutors said.

Mouzon and Brockington both face maximum prison terms of 20 years and fines of $250,000, prosecutors said. Sentencing is pending.