The boyfriend, Officer Terry Pena, had already resigned from the Galena Park department, KPRC-TV in Houston reported.
Corrie Long says, in the complaint to the U.S. Equal Opportunity Commission, that the chief, Robert Pruett, interrogated her in detail about sex acts and locations with the photos visible on his desk.
"The chief didn't protect her from it," her lawyer David Tang told the TV station. "He called her in and just re-victimized her again by exploring her sexual history and threatening to expose these photographs if she didn't resign."
Pruett said the incident was handled in a "professional manner." He said Pena was originally suspended for 10 days and Long for five when he discovered they were dating, a violation of department rules.
Pena allegedly e-mailed him the photos while he was suspended.
The couple apparently gave different versions of where the photos came from. Tang said they were taken before Long joined the department and Pena sent them to the chief because Long had broken up with him, while Pena says he was the one who ended the relationship and Long sent him the photos in an effort to convince him to resume it.