Williamson, 48, waived his right to a jury trial just two weeks after being charged. He signed a plea agreement in which he promised to pay $10,000 in restitution. A sentencing date has not been set, but Williamson could receive up to 20 years in prison and a fine of $250,000 for mail fraud and deprivation of honest services, U.S. Attorney Edmund Booth said.
Williamson, who did not run for re-election last year after a two-term limit, was released on $10,000 bond.
"I'm just glad it's over," he said outside the federal courtroom in Dublin.
FBI agent Robert Jones testified that a joint investigation by the FBI and GBI produced evidence that Williamson collected fines that were never paid to the probate court and that he kept $5,000 seized in a traffic stop. The sheriff also mailed a letter and a check drawn from a county account to make a monthly payment on an all-terrain vehicle kept for his personal use, Jones said.
Williamson was also accused of accepting money to get a Telfair State Prison inmate transferred to the county jail so that the inmate "could spend time with his girlfriend," Jones said.
Williamson told U.S. District Judge Dudley Bowen that he denied accepting money from the inmate and pocketing cash from the traffic stop but still wanted to plead guilty.