The Sheriff's Department said the 24-year-old woman voluntarily had sex with Deputy Garry D. Jackson, but Michigan law makes sexual contact with prisoners a crime because they can't give consent.
The 52-year-old deputy has been a jail guard since 1997. He was arraigned Monday on a charge of second-degree criminal sexual conduct, which can carry a penalty of up to 15 years in prison.
Jackson is free on a $5,000 personal bond. Undersheriff Michael McCabe said the Sheriff's Department is moving to fire him.
"Jackson has brought dishonor to the badge and violated public trust," McCabe said.