Bruce Karatz could not have relied on advice about stock-options backdating from KB Home’s general counsel because he lied during an internal investigation into the practices, federal prosecutors argued in attempting to quash the former chief executive’s motion for a new trial.

“Rather than establishing defendant’s good faith reliance on an attorney, the record readily establishes that defendant used Hirst to perpetrate a fraud,” prosecutors wrote in papers filed with the court on Monday, referring to General Counsel Ben Hirst.