Detective inspector Chris Simpson was speaking on a panel at the Infosecurity Europe conference in London.
"Who are the culprits of computer crime?" he said. "It's current or former employees who want revenge." Simpson went on to add that poor security policies leave companies open to computer crime.
But Richard Cox, chief technology officer at anti-spam lobbyists Spamhaus, insisted that computer crime was being exacerbated by the inactivity of ISPs and people's failure to report crime.
"People don't report dial-up scams because they think they're connected to porn sites," said Cox. He then added that many ISPs are not in touch with their customer base and that their abuse departments are ineffective. Three American ISPs were singled-out for particular derision.
Robin Urry, of the European Commission's Joint Research Centre agreed more needs to be done to help prevent computer crime. "Organised crime gangs are trading botnets the same way people used to trade pistols," he said. "Computer crime is on the rise."
Earlier today SC reported another member of the CCU would be following detective sergeant Steve Santorelli to Redmond to join Microsoft.