Brooks Kellogg is accused of trying to hire a man to kill a former business partner.
The FBI arrested him in Denver last fall after he allegedly gave money to an undercover agent.
The FBI admits a video camera used to record the meeting didn't work.
Kellogg's lawyers are accusing the government of misconduct.
A Denver newspaper reports that the government's key witness, Kellogg's mistress, turned out to be a convicted felon who initiated the plot.
The FBI says the case should still proceed because Kellogg eventually went along with the idea.