Seven law enforcement agencies have been tracking the suspect. They say he's now attacked at least 30 women, and there may be more.
The owner of an Inland Empire massage parlor, who asked not to be identified, says she was the victim of a man with a gun.
"He came in and he asked me for a massage, and I said, 'I'm busy now.' He said, 'That's OK, I can wait for you,'" the woman said.
But she says she later saw on her security camera that he did not stay in that room while she was with another customer. Instead, he cased the entire building and finally knocked on the door of the room she was in and motioned for her to follow him.
"He take the gun out and he put it in my chest. He said, "Give me money! Give me money!'" the woman said.
But she says just when things were about to get really ugly, another customer came in, and the suspect ran out the back door.
"Suddenly another customer came in. Yeah, lucky!" she said.
Though police have not corroborated that her attacker is the serial rapist and robber they're looking for, they say the same man has attacked at least 30 victims, mostly targeting massage parlors over the past few years around Riverside, San Bernardino and Los Angeles counties, and the manner of operation is similar.
"The same DNA matched several cases from different other counties," said Riverside Police Officer Javier Cabrera.
Police say the nature of the sexual assaults has also been the same - first engaging the victim in conversation before sexually assaulting and robbing them.
"He would lure them to the room, that's where the sexual assaults occurred, and then he would rob the business and the employees," said Cabrera.
The business owner says she has a friend who was also targeted by the same man, and now she keeps the door locked at all times.
"I was scared, so scared," she said.
Police are planning to release video and photos of the serial rapist at a news conference at the Magnolia station in Riverside Wednesday morning, asking for the public's help to find him before he hurts anyone else.