A San Francisco man was arrested and charged with two September armed robberies that turned into assaults involving sex workers and johns in Oakland's unofficial red-light district.

Much like San Francisco has certain blocks of Shotwell Street, and formerly Capp Street, in the Mission that are known for sex workers plying their trade, Oakland has International Boulevard and certain blocks surrounding it that become a red-light district every night.

As San Francisco police have done in the last couple of years, Oakland police installed barricades on East 15th Street last year to deter rampant sex work there. But, the sex workers just moved elsewhere — as they did in SF. And this latest story comes from a September 10 incident that occurred on East 10th Street in Oakland, where a john may have driven with a sex worker to have an intimate encounter.

As Bay Area News Group reports, a suspect armed with a knife confronted the man and the woman inside the car, demanded their money, stealing $250 in cash, but after he demanded the male victim's car keys, the victim fought back, sliced his hand on the knife while trying to grab it, and then drove off, leaving the suspect and the female victim behind. The suspect then allegedly demanded a blowjob from the woman at knifepoint — and the encounter was captured on surveillance video.

Eight days later, on September 18, a second, similar incident occurred one block away. The assailant in that incident similarly attacked a sex worker and a john who were getting down to business, stealing money and condoms from them, and then forced the sex worker to orally pleasure him.

Oakland police officers, who have been enagaged in a "surge" in recent months cracking down on sex-trafficking and sex work along International Boulevard, were nearby when the September 18 incident occurred, and a witness called 911 as it was unfolding.

The officers apparently confronted the suspect as he was assaulting the sex worker, but he fled on foot and managed to lose them, as Bay Area News Group reports. This time, though, he left behind his car, a Kia Sportage.

Using that, and phone records, police were able to identify the suspect as 54-year-old Cory Butler of San Francisco.

There is some online evidence of a Cory Butler having a history of law enforcement encounters and incarceration in San Francisco, though it's unclear if it is the same person.

Butler has been arraigned and he pleaded not guilty to a slew of felonies including kidnapping, forcible oral copulation, robbery, and attempted carjacking. And Butler apparently has a prior second degree robbery conviction. He's being held at Santa Rita Jail.

Bay Area News Group reports that Butler's attorney filed a motion to prevent Butler from being compelled to appear in court for a preliminary hearing — a move that's being interpreted as making it more difficult for victims to identify him.

It's not clear if police believe Butler may be linked to more than just these two September assaults and robberies.