Delaware State Police said 32-year-old Kevin Hovatter was arrested following an investigation prompted by an anonymous tip.
Investigators said Hovatter met the victim, now 28, after a domestic incident between her and her boyfriend and touched her inappropriately at the police station.
The victim met with Hovatter over the next two years for fear of being arrested, and Hovatter allegedly committed inappropriate acts with her during those meetings.
Hovatter was indicted Monday on charges of rape and sexual extortion and was being held on $40,000 secured bond.
Hovatter was charged in 2006 with raping a woman after making a traffic stop. He has been a registered sex offender since 2007.