Detectives said the suspect is 29-year-old Pedram Mehrian of Los Angeles.
Investigators said a woman reported that Mehrian responded to an Internet escort advertisement in early June. He posted bail and was released, facing a hearing in July.
"When they met at this location, he sexually assaulted her," said Sara Faden of the Los Angeles Police Department. "He presented himself as a police detective, had what looked to be an official LAPD badge, handcuffed her and sexually assaulted her."
Officials said they arrested Mehrian June 2 on suspicion of sexual assault for a similar incident in May.
Detectives were also investigating a third assault that happened in a similar fashion in May in West Los Angeles.
Mehrian was behind bars Saturday in lieu of $1 million bail.
Police said he may have other victims. Anyone with information on Mehrian is asked to call the LAPD at (877) 527-3247.