According to the indictment, Dean exposed himself and inappropriately touched one of his adopted daughters between September 2008 and October 2010.
After news of the indictment broke, Dean resigned his seat on the commission.
The state Division of Family and Children Services removed four children from Dean's Harlem home in October. The children later were returned, but Dean was required to live elsewhere and was granted only visitation rights.
Dean and his wife, Renee, have seven children, five of whom they adopted from Guatemala in 2008.
The DFCS investigation was prompted when the Deans' 17-year-old adopted daughter, Marlin, ran away from home to Mexico. However, the indictment doesn't name her as the alleged victim.
Marlin was last seen Oct. 19 near Augusta Mall. Since then, she has posted messages on Facebook defending her father.
A phone message left for Dean was not immediately returned Wednesday afternoon.
Columbia County sheriff's Capt. Steve Morris said Dean is expected to surrender to authorities this week.
A bond hearing is scheduled for 10 a.m. Friday at the Evans courthouse, said District Attorney Ashley Wright.
After receiving Dean's resignation letter, commission Chairman Ron Cross said he called all other commissioners and each agreed to accept the resignation.
"Due to my family and legal issues and to allow for continued representation for the citizens, I am making the decision to resign effective immediately," Dean wrote in his letter.
"I am still confident that I will be vindicated, and I ask for the media to please allow my family the privacy that they deserve," he added.