It's no secret that the FBI has plenty of fancy tools to ply its crime-fighting trade -- high-speed computers, digitized color mug shots, automated fingerprint identification systems, sophisticated snooping devices.

But one tool has pretty much stayed a secret at the FBI. Special agents call him "Marvin," a beeping, blinking robot straight from a Jetsons cartoon script who delivers thousands of pieces of mail every day at the FBI's Baltimore field office.

"He's a very capable G-man robot," FBI spokesman Larry K. Foust says.

Marvin follows a path of invisible fluorescent paint sprayed on the carpet as he weaves his way through the maze of offices at the FBI building near Security Square Mall.

He beeps as he approaches his designated mail drops. Agents and secretaries say they better watch out.

Sometimes, Marvin stops for no man or woman: armed or unarmed.

"When he goes around the corner, and you're going in the other direction, he'll pin you against the wall," says Debbie Cosden, a civilian FBI supervisor and Marvin's boss.

"He has run into some people."

Still, Marvin is considered to be a model employee by most at the FBI.

Agents and secretaries say he always comes to work. He's the first one in, and the last to leave.

He never takes a cigarette break. He doesn't ask for raises. He has no family worries.

"He never complains," Foust says.

Marvin is known as a Mailmobile, a member of a family of robots that made its first appearance 20 years ago in the Chicago offices of Sears, Roebuck and Co. in what was then the tallest building in the world.

Since then, nearly 1,000 Mailmobiles with such nicknames as Luke Carpetwalker and Cliff Claven -- no one knows how Marvin got his name -- have been making their appointed rounds in corporate and government offices in the United States and Canada, and a few countries overseas.

Lifts 800 pounds

The FBI transferred Mailmobiles from its Washington headquarters to field offices around the nation in 1992. Agents and secretaries in the Baltimore division say they're happy to have their very own Mailmobile.

Marvin weighs 600 pounds. He's 4 feet tall. He can haul up to 800 pounds of mail. He has cells of black lights beneath his metal frame that read the invisible fluorescent path sprayed on the carpet of the FBI field office.

He beeps and flashes as he follows the path. A bell rings when Marvin reads a bar code on the floor, telling him when to stop for mail drops at 19 "squads" within the field office. Secretaries have about 30 seconds to take their mail from Marvin before he heads to his next stop.

Marvin and other Mailmobiles were developed by Lear Siegler Inc., the company that invented the Learjet. Bell & Howell Co. bought the robot division in 1980, and it has been turning out Mailmobiles ever since from a plant in Zeeland, Mich.

Besides the FBI, Mailmobiles are making their rounds at Potomac Edison in Hagerstown, Northrop Grumman Corp. in Linthicum, State Farm Insurance in Frederick and the International Monetary Fund in Washington.

'Bells and whistles'

Each robot costs between $22,000 and $80,000, depending on the number of features, which can include devices that open doors and summon elevators, allowing the machines to deliver the mail without help from humans, says David E. Michaud, president of Mailmobile Co.

"Some of them have a lot of bells and whistles," Michaud says.

While Marvin isn't as souped-up as the latest generation of Mailmobiles, FBI workers say they have become attached to him. So have the children of FBI agents and the schoolchildren who tour the field office. "The kids really adore him," Foust says.

But Marvin is getting on in years. Aside from his motion detector failing to pick up pedestrians in his path, Marvin has been known to break down. He'll work hard for six months, and then he may take two weeks off -- unannounced.

"He has his ups and downs," says Cosden, Marvin's boss, "just like anyone else."

Pub Date: 9/16/96