The federal investigation into the truck stop chain owned by the family of Tennessee Gov. Bill Haslam and Cleveland Browns owner Jimmy Haslam led to its first convictions this week and threatens to widen against employees at Pilot Flying J.

Court documents allege that sales teams were being trained on how to scam the company's customers out of rebates and get away with it.

Pilot's regional sales director and regional accounts representative both pleaded guilty Wednesday to conspiracy to commit mail fraud. The pleas were entered in U.S. District Court in Knoxville. Prosecutors have offered to recommend a much lighter sentence for both employees provided they cooperate with federal investigators and reveal the extent of how many people in the company knew about the fraud.

The Knoxville-based chain is run by CEO Jimmy Haslam, the brother of Tennessee Gov. Bill Haslam. Pilot Flying J, the country's largest diesel retailer with annual revenues of $31 billion, was founded by their father.

Jimmy Haslam has denied any wrongdoing and has suspended several members of the sales team, but he has declined to identify exactly who has been suspended. An affidavit unsealed last month shows that a Pilot employee was secretly recorded saying Jimmy Haslam knew what sales people were doing, though he has denied knowing of any fraud.