Federal authorities released a sketch Tuesday of a man being sought in connection with the mailing of two explosive devices to companies in Chicago and Kansas City, Mo.

The man depicted in the drawing was last seen in the lobby of a suburban Chicago post office on the day the packages were mailed, according to the U.S Postal Inspection Service, which has offered up to $100,000 as a reward for information about the devices.

David Colen, a spokesman for the Inspection Service's Chicago division, said the man, who was wearing tan pants and a dark gray or olive military-style jacket, is a "person of interest."

"All I know is, he was in the post office," Colen said. "He was there at the right time."

Two packages containing explosive devices and threatening correspondence were sent Jan. 26 from a post office in Rolling Meadows, authorities say. Officials have suggested in both cases that the devices were not working bombs that could have exploded.

One of the packages arrived Jan. 31 at American Century Investments' midtown Kansas City mail facility. The next day, a similar explosive was found at a business in a 65-story skyscraper in downtown Chicago.

The sketch was developed with the help of a witness who was in the lobby of the Rolling Meadows post office when the packages were mailed, Colen said.

The Postal Inspection Service said the person suspected of sending the explosive packages has at times identified himself as "The Bishop." The agency also said the suspect may be linked to other threatening letters received by various financial institutions during the past 18 months.