The founding father of the UK's computer forensic industry was today sentenced at Leicester Crown Court for making false witness statements and committing perjury.

Jim Bates, 67, was found guilty on the 6 March of four counts of making a false written witness statement claiming he had a degree in electronic engineering, and one count of perjury.

The top expert IT witness was sentenced today to six months in jail for each of the five offences. All the jail sentences were suspended for two years. Bates was also ordered to pay £1,000 towards court costs.

Bates had acted as an expert witness, for both prosecution and defence, in dozens of serious investigations including child pornography and rape. In the 1990s the police employed him as a lecturer at the Bramshill Training College in Hampshire, and he also sold his proprietary forensic imaging software to several forces.

Judge Hammond, who presided over today's hearing, said: "I am quite sure that his career as an expert witness has now finished."

After working closely with the police for a number of years Bates appeared as a defence witness for people caught up in Operation Ore, the police investigation into UK users of a US-based site that sold images and video clips of child porn. He is highly critical of the operation, but senior police officers gave evidence in his support at his trial.

Bates was MD of his business Computer Forensics, which he shut down in 2002. He has used his company website to suggest that many of the 4,000-plus men arrested in the Ore sweep may have been innocent. In the past he has used his site to attack the technical competence of other expert IT witnesses and hosted it outside the UK to avoid legal requests to take it down. His site, www.computer-investigations.com, is currently suspended but carries the quote: "Twisted by knaves to make a trap for fools."

Bates also worked as the defence expert for Detective Constable Brian Stevens, the police family liaison officer attached to the family of one of the murdered Soham schoolgirls Holly Wells and Jessica Chapman. Stevens was arrested as part of Operation Ore on charges of possessing child pornography. The case was dropped after Bates' work led prosecution lawyers to admit that their expert witness had made "substantial errors" and reached a "wholly false" conclusion in his analysis of the officer's laptop computer. Stevens was later jailed for falsifying his alibi to escape the charges.

Bates was also involved in the investigation of Gurpal Virdi, a Sikh police officer with the Metropolitan police, who was accused in 2000 of 14 counts of sending racist letters to himself and several colleagues. Bates' work supported this accusation, but an employment tribunal found in favour of Virdi and reinstated him.

Bates does not believe his conviction raises questions about the quality of any evidence he has given. To some extent his peers back him up. Professor Peter Sommer, a visiting research fellow at the London School of Economics and an experienced expert witness, has worked on opposite sides of trials to Bates. " In the cases I did against Jim Bates I've got no basis for thinking the people were wrongfully convicted," he said.

Computer consultant Professor Neil Barrett, currently employed by the EU as a trustee to monitor Microsoft, said: "In the cases I worked on he put together a good competent evidence package. Jim was very good at putting together clear presentations. I was pleased with the work that he did."

"There is no evidence that anyone has suffered from the evidence that he gave. His experience was sufficient to justify his status," added judge Hammond.

"There is no doubt as to his expertise, he was no charlatan."