ATHENS, Ga. >> A man posing as an Uber driver at the University of Georgia is accused of sexually assaulting women he picked up in his vehicle, authorities said.

A 21-year-old student got into the minivan of Emerson Redd, 53, outside a downtown Athens club early Friday thinking it was the Uber she had called, Athens-Clarke County police said. She got suspicious when she saw the vehicle was missing a GPS device, so she took pictures of the driver and demanded to be let out when he touched her inappropriately. The driver let her go.

About an hour later, police say, Redd picked up another university student and raped her. He has been charged with rape and sexual battery.

The first victim alerted officers after police posted a notice about the rape on Facebook, Athens-Clarke County police Capt. Jerry Saulters told news outlets. Police say they feared the suspect might attack others if not apprehended quickly.

“Our concern early on was he would strike again so we worked this case hard,” Saulters told The Athens Banner-Herald . “We had detectives who worked this case for 24 to 30 hours straight.”

Pictures taken by the students helped police break the case, they said.

Detectives spent hours scrutinizing the photos that showed portions of the interior of the suspect’s vehicle before determining it was a Chrysler Pacifica minivan, Saulters said.

He said that it appeared the suspect might have chosen his victims by cruising downtown Athens looking for young women holding cellphones to their ears while appearing to be waiting on a ride.