HOUSTON -- A man pretending to be a U.S. postal worker is committing robberies in the Houston area, officials told KPRC Local 2 Wednesday.

Crime Stoppers and the U.S. Postal Inspection Service asked for the public's help in identifying the robber.

Officials said on March 26, a man wearing a postal uniform entered the EZ Pawn shop at 5901 Lyons St. and looked at some jewelry. The man then grabbed all five pieces and fled the store, according to authorities.

"He was acting friendly. He didn't look suspicious and he grabbed the merchandise and left," said Katherine Cabaniss, the executive director of Crime Stoppers.

The man attempted a similar robbery earlier in the day at the EZ Pan on Interstate 10 at Lockwood, but he left the store when the clerk asked for identification, officials said.

He is also believed to be involved in a similar case that happened in October at the Medical Center Station post office, where a clerk was assaulted during an unsuccessful robbery attempt.

"The fact that he was wearing a uniform gave him access to our station," said George Alpizar, a postal inspector.

"We're working with the postal inspectors, trying to figure out who put on a postal uniform and went and robbed an EZ Pawn," Cabaniss said.

Surveillance video captured a grainy picture of the robber, who is described as a black man, 21 to 25 years old, 5 feet 10 inches to 6 feet tall, with a slim build and wearing a baseball cap.

Crime Stoppers will pay up to $5,000 for information leading to the identification, arrest and charging of a suspect. Anyone with information is asked to call 713-222-TIPS.