The chairman of a company that trucks mail between postal centers says the FBI has reviewed his firm's employee records as part of an investigation into ricin found at a Greenville, SC, mail center, The Associated Press reported.

Federal agents wanted the records of workers and truckers who had access to the mail center where the deadly poison was left in October, said James R. Malone, chairman and CEO of Mail Contractors of America.

Mail Contractors, Little Rock, AR, has about 1,400 employees, most of them truckers. The company has been carrying U.S. mail for more than 40 years. However, Malone said his company no longer runs the route involving the airport postal center.

"Clearly, we would be very willing and enthusiastic about helping with the investigation in any manner, shape or form," Malone said. "Obviously, we want whoever it is to be caught as quickly as possible."

Meanwhile, federal agents are still offering a $100,000 reward in the case.

A letter accompanying the ricin found at the mail center and a similar letter containing ricin intercepted before it reached its intended destination at the White House complain about new federal trucking regulations.

A small amount of ricin also was discovered on a mail-opening machine in the Washington offices of Sen. Bill Frist, R-TN, two weeks ago, but investigators have not been able to trace that ricin to any letter or envelope.