Police in one major U.S. city say they have seen a dubious trend in one particular area of theft.

Crooks in Houston have combined stealing cars with identity theft. Officials say criminals are stealing the identity of ordinary citizens, and using that information to rent cars they have no intention of returning. Many of the rental cars are either sold on the black market or used in committing other crimes.

If thieves have credit card information and even a doctored driver's license, it's often been enough to fool rental-car employees, who walk away with keys to a rental car.

Rental cars fetch thieves about $700 per car, according to KHOU-TV, which launched an investigation into the problem.

"That's pretty much the going rate," Houston Police Department offier Jim Woods told the news outlet. "Any stolen vehicle is going to be sold for less than $1,000."

The cars are also being used in the commission of other crimes. For example, a stolen Ford pickup was used in an armed robbery at a T-Mobile store last week in northeast Houston. Some of the cars are also being sold to unsuspecting used-car customers on sites like Craigslist.