The FBI has acknowledged the use of computer forensics software in its efforts to smash a US credit card and counterfeit travellers' cheque ring.

Saleem Shirazi and an accomplice were initially apprehended by Chicago police in 2000 after an anonymous tip-off.

On searching Shirazi's motel room, police found weapons, drugs, a stack of counterfeit travellers' cheques and a laptop and desktop computer.

Recently filed court papers indicate that Shirazi, who has been convicted on two counts of conspiracy, was brought down on evidence found in his computers.

The FBI received a warrant to search the computers and 74 floppy disks recovered from the room. The search, which used Guidance Software's EnCase product, also identified several dozen images of child pornography.

"The importance of digital evidence is becoming increasingly vital in cases ranging from corporate fraud to national security," said Guidance Software chief executive John Colbert.