Microsoft's billion-dollar bet on a Norwegian search-software company was troubled before it began, and it quickly went downhill from there.

Now it has become a criminal matter. Officers from Økokrim, the Norwegian authority for the investigation of economic and environmental crime, raided the Oslo offices of the company, Fast Search & Transfer, and seized documents.

The raid last week was prompted by an investigation into what began several years ago as a seemingly routine earnings restatement but has now developed into a full-blown criminal investigation that could put a Microsoft executive behind bars.

Microsoft paid $1.23 billion for Fast last January to acquire the company's cutting-edge search technology, which Microsoft sees as a crucial weapon in its war against Google.

The growing scandal over Fast's finances presents increasing risks for Microsoft.

"The key point is that Microsoft Fast is not in control. Control has shifted to the police," said Stephen E. Arnold, an industry consultant who writes a blog called Beyond Search. The episode, while hardly fatal to giant Microsoft, does raise questions about the company's ability to conduct due diligence in M&A, an increasingly important area.

Among technologists, Fast was respected as the Google of Norway. It has been a leader in the market for the largest-scale corporate and governmental search customers. Its clients have included Comcast, the Walt Disney Co., the Financial Times, and AT&T. Google dominates the search market for consumers and medium-size businesses, but the high end is up for grabs.

Unfortunately, Fast also has earned unfavorable comparisons to Enron. It was forced to restate its revenue for 2006 and 2007. For the latter year, its last as an independent company, Fast ended up with a loss of $135 million on revenue of $143 million.

As of last January, when the Microsoft deal was announced, Fast said it expected 2007 revenue of $161 million. The accounting problems stemmed from the practice of booking revenue from deals before customers actually paid.

Last May, financial regulators in Norway referred the matter to Økokrim; its six-month investigation culminated in the charges and the October 13 raid.

So far, Microsoft is taking the criminal charges in stride. The company issued a statement after the raid saying that the actions by Økokrim concerned Fast accounting practices in 2006 and 2007.