WFAA-TV

Mario Romero, a man who looks like a woman, was arrested for trying to sell sex to other men.

Selling sex - it's not as discreet as you think.

Fort Worth police say they face a growing problem - escort services that are a cover for prostitution rings.

Mario Romero, a man who looks like a woman, was arrested for trying to sell sex to other men. Arrested because undercover Fort Worth police detectives are cracking down on escort services.

He was arrested in a sting operation at a Fort Worth motel.

Investigators say he placed an ad on Craigslist. Romero is one of nearly a dozen prostitutes recently arrested.

"A lot of times it's called escort services, but it's the same thing as prostitution," said a police spokesperson.

Investigators say online escort services have become a bigger problem, than street prostitution. They say some street prostitutes are now placing explicit ads on Craigslist and Backpage.com.

Serina Crocket made $17,000 a month.

"The high price ones really do this as a way to pay for the kids to go to college, pay for a certain lifestyle they're accustomed to. But on the lower end of the scale, it's usually for drug money or criminal enterprises," a police spokesperson said.

Both Craigslist and Backpage say they do not condone illegal activity and work closely with police.

E-mail dmiles@wfaa.com.