Authorities said the women got into the suspect's car voluntarily, but soon after they realized they were in danger.
The suspect allegedly drove them out of the city into the county. He allegedly beat them, severely choked one woman, and drew a knife on another. The suspect allegedly raped two victims and tied one of them up.
"That particular case, the victim was found walking down an eastern Wake County roadway with her hands duct taped behind her back," said Lt. Steve Hale of the Wake County Sheriff's Office.
Officers say they are almost certain they are looking for one man. They think he may have attacked other prostitutes, and they fear those women will not come forward.
"Prostitution is against the law, so to cooperate with the very people that are going to arrest you for committing crimes is obviously a contradiction," said Lt. Ken Mathias of the Raleigh Police Department.
Officers say they have a vague description of the attacker -- a black man with a balding or shaved head. Some victims say he drives a black Acura while others say a white Camaro.