A SENIOR Government scientist only learned details of an investigation into his expense claims when police knocked on his door, a court heard.

Dr Michael Wilson is accused of swindling his employer - the Central Science Laboratory (CSL), based at Sand Hutton, near York - out of thousands of pounds to fund his computer hobby.

Wilson headed a team of 100 people with an annual budget of £6 million to £7 million and travelled abroad to promote the agency and speak at conferences.

He is alleged to have siphoned off about £13,000 from the CSL over a number of years to buy games, computer parts and equipment for his own use. He has pleaded not guilty.

But CSL's finance director Richard Shaw, speaking at York Crown Court yesterday, said his department did not tell Wilson about a Government auditor's investigation into his expenses claims.

Mr Shaw said he was following a due process, adding: "There could have been an explanation. It was not my decision."

He told the court his department had not found any irregularities in Wilson's expenses before auditors started a review of CSL's finances in November 2004.

Earlier prosecutor Simon Kealey had told the court that Wilson falsified receipts, blanked out parts of credit card statements and other documents.

Wilson, 53, of Park Gate, Strensall, denies 22 charges of obtaining money transfers by deception between May 3, 2001, and November 19, 2004.

Mr Shaw said Wilson was a trusted and senior civil servant who was issued with a credit card and allowed to sign off his own expenses.

Joel Smith, head of information systems at CSL, told the court that many of the items bought by Wilson did not have a work use.

The list included a joystick, an aquarium screensaver, ink cartridges, mobile phone traffic-alert software, virus scanning programs, a broadband modem, a Freeview TV set box and Apple IMac parts.

Mr Kealey said Wilson had ordered about 70 computer components, including seven monitors.

Mr Smith said the parts could make up about seven computers, saying: "Those would not be the normal items we would purchase.

"Those are components for building PCs from scratch rather than repairing old ones."

He added: "I would be surprised to see someone coming in with a home-built PC because we buy everything centrally."

The analytical chemist was in charge of the then pesticides and veterinary medicines group and headed a team looking into contaminants in food.

The trial continues.