The allegation was made during an intermediate diet of the case against Terence Horan and Jane Hagan, who worked at the millionaire's property Castle Grant.
Hagan, 50, and her partner, 53-year-old Horan of Grantown, appeared for the second time at Inverness Sheriff Court, continuing their pleas of not guilty to stealing items from Castle Grant between June 1 and September 7, 2012.
Both are alleged to have stolen items including a quad bike, quantities of coins and Dutch guilders, a silver photograph frame, a hip flask and cups, three sets of cufflinks, a fuel card, a telescope and a case.
The intermediate diet was called so Sheriff David Sutherland could receive an update on the progress of the prosecution and defence case for the trial which had been fixed for March 4, 2013.
But Public Defenders Solicitors Office lawyer Eilidh Macdonald told the court she was seeking new dates to be fixed because of a problem with the Crown disclosing its evidence to the defence.
She said: "There has been partial disclosure by the Crown and reference has been made to a letter which the complainer [Whyte] produced from a computer which is owned and operated by the accused and purporting to be from the accused.
"I have that computer in my office and there is a suggestion the letter has been falsified. So the computer may have to be analysed."
Sheriff Sutherland said a further intermediate diet will now be held on May 14 with the trial scheduled for June 10.