A man posing as a taxi driver has been picking up passengers and robbing them of their cash and jewelry, according to D.C. police crime reports.

At least five such robberies were reported in the District between Oct. 16 and 27, according to the reports. Police officials refused to comment on the incidents because they are under investigation.

Daisy Voigt, a spokeswoman for the D.C. Taxicab Commission, said its staff recently received a complaint from a passenger who alleged robbery by a driver. She said the commission's initial investigation revealed that the cab had been stolen.

In the first robbery, a woman riding in a cab was driven to Branch Avenue and Pope Street SE at 1:35 a.m. Oct. 16, according to the reports.

Once there, the driver refused to give the woman change for her $20 bill. He then beat her, ordered her to disrobe and stole a blue jacket, a blouse and a pair of pants from her, according to the report.

Three days later, at 10:40 p.m., another passenger was robbed of cash in the 5800 block of Fourth Street NW, according to the report.

On Oct. 19, a driver told a passenger that he had a gun and robbed her of cash, a ring and a watch in the 1400 block of 10th Street NW, according to the report. That incident occurred about 11 p.m.

Two days after that, three people were picked up about 3:50 a.m. by a driver who told them he was a murderer and robbed them of their jewelry at Sixth Street and Massachusetts Avenue NW. Then, on Oct. 27, a passenger in a cab was robbed of $10 and two rings in the 400 block of Elm Street NW.

Managers of local taxi companies said tracking such assailants often is difficult because many passengers do not notice the name of the cab company or whether their driver is displaying a valid taxi license. D.C. law requires that all drivers keep visible photo identification in their cabs.

"People are sometimes so anxious to get a cab that everything else doesn't matter," said Reginald Luckett, acting business manager of Capitol Cab Cooperative Association. "If you have a cab {company name} and a number, that's enough for us to be able to track down any driver."

Other cab company managers said this is the first time they had ever heard of a driver robbing a passenger. To be licensed to operate a cab in the District, drivers must be screened by the FBI, they said.

Voigt advised passengers to check to see that their driver is a licensed cab operator.

"If they give you trouble {when} you ask for identification, you certainly shouldn't be riding with them," she said.