A grand jury decided not to charge anyone in a public sex act near Ohio University that was photographed by witnesses and later reported by the woman involved as a sexual assault after images circulated on social media, a prosecutor said Monday.

Athens County Prosecutor Keller Blackburn said the grand jury determined there wasn't probable cause to file charges after a man and woman were photographed and recorded in a sex act against the window of a bank near the southern Ohio campus in the wee hours of Oct. 12. Explicit photos of them were circulated via social media, and the woman later told police she was a victim of a sexual assault.

Investigators determined the couple, both 20-year-old students, had alcohol from a bar before the sex act, Blackburn said in a statement Monday. Blackburn said the man asked the woman whether to stop the act when a crowd formed, and she said no.

The man has cooperated with police. The woman didn't remember what happened, and testing showed no sign of any "date rape drug," Blackburn said.

Blackburn said the students weren't aware at the time that their act was being filmed.

"Every decision we make now has the potential to be placed on Twitter, Facebook, commented on, shared and embellished, making life today more public than ever before," Blackburn said in the statement. "If a lesson exists from this case, let it be that we should behave as if our family is always watching."

Ohio University President Roderick McDavis said earlier that the school about 70 miles southeast of Columbus would conduct its own investigation and, if appropriate, hold people accountable.

A statement from the university said it is following its own procedures to look into the report of alleged sexual misconduct, and the details of that investigation aren't public.

"Each of us has a responsibility as a contributing member of the community to understand how to recognize behavior that is unsanctioned and unlawful and then become empowered to address it," the university said.

Blackburn said the use of social media not only documented the couple's behavior but also contributed to the spread of false rumors in the case and the misidentification of another student as being the woman involved.

Photographs circulated online also played a big role in a rape case in eastern Ohio as Steubenville police investigated two high school football players. A judge convicted the teens of rape in March.