Millionaire 'who hired spied on Jimmy Choo queen tried to use insider trading to make a fortune'

Active Investigation Services (AIS), who are accused of hacking into shoe empire boss Tamara Mellon's e-mails, paid an American computer expert to target a quoted company on the London Stock Exchange.

Southwark Crown Court was told a mystery client known only by the suspected pseudonym Len Michaels had asked the agency for any embargoed information that would give him "an edge in share dealing".

But the unnamed company's main frame security features eventually forced AIS to allegedly concentrate on a press agency instead.

Miranda Moore QC, prosecuting, claimed the new plan was to download press releases up to 20 minutes before publication.

However, success was again in short supply, and the only deal that resulted lost £4,000 anyway, said the barrister.

Then, not long after that AIS's virus was discovered and prompted a "rather nasty" response.

Arizona-based hacking expert Marc Caron warned the private investigators outraged press agency staff had threatened they would "hunt us down like the dogs we must be and bugger us with sharp sticks".

He added: "We need to leave these guys alone for 30 days...we underestimated our opponent." Jurors have heard Mellon, heir to a four billion dollar (£2 billion) oil and banking fortune, turned to the company in 2004 during his "acrimonious" divorce from Tamara, former It Girl and now head of the Jimmy Choo footwear empire.

He allegedly thought it "would be a good idea" to hack into her computer and access her emails in the hope of discovering information unavailable through the "court process".

The court has heard an email, sent to the businesswoman, contained a so-called "Trojan" virus designed to record every keystroke she made.

AIS, partly run by moonlighting Met policeman Jeremy Young - who has admitted overseeing the agency's "illegal sidelines" - is also said to have been involved in other disintegrating marriages, as well as industrial snooping and a family business dispute.

Mellon, 43 and now divorced, of Belgravia, central London, denies one count of conspiring to cause unauthorised modification of computer material between July 1, 2004 and February 4, 2005.

The two-month trial was adjourned until tomorrow when the Crown is expected to conclude its opening address and call a BT telephone tapping expert to give evidence.