No charges have been filed yet. Prosecutors say the investigation stems from accusations that the company knew its products were defective but misled customers and investors. Investigators also are reviewing whether the company misled lenders. The investigation is separate from a review by some U.S. House members including Republican Cory Gardner of Colorado.
A former company executive didn't immediately return an email seeking comment Thursday.
The Loveland-based solar panel manufacturer filed for bankruptcy protection this summer and laid off about 125 workers.
It received a $400 million loan guarantee from President Barack Obama's administration and had received about $70 million before its credit line was frozen.
(Copyright 2012 by The Associated Press. All Rights Reserved.)