DATAllegro, a data warehousing appliance vendor that is being acquired by Microsoft, was accused Tuesday of using now-patented database technology that was developed by a San Diego-based startup where DATAllegro's founder and top executive briefly served as CEO.

In a complaint filed Tuesday in U.S. District Court in San Diego, Cary A. Jardin, founder of a company called XPrime, claimed that DATAllegro CEO Stuart Frost used his access privileges while he was at XPrime in 2003 to steal information about technology that Jardin was then in the process of patenting. Frost founded DATAllegro in June 2003.

The lawsuit says that the patent, titled "System and Method for Generating and Processing Results Data in a Distributed System," was issued by the U.S. Patent and Trademark Office on February 13, 2007, to Jardin as the sole inventor.

According to the suit, Frost "attempted to convert Jardin's inventions to his own by filing with the USPTO patent applications in the distributed database architecture field, the same subject matter as Jardin's intellectual property." Moreover, the suit alleges that Frost "used and incorporated Jardin's intellectual property into DATAllegro's products," adding that the unauthorized use of the technology "continues to this day."

Neither Frost nor Microsoft officials were immediately available for comment on the suit. Microsoft last month announced that it was buying DATAllegro, which makes high-end data warehousing appliances, to bolster the high-end business intelligence capabilities of its SQL Server database for users with multiple terabytes of information to analyze.