Another city employee involved with Chicago’s Hired Truck program has pleaded guilty to federal charges.

Patrick Stillo, a former foreman for the city, pleaded guilty on Tuesday, Aug. 9, to charges of mail fraud and robbery. According to the Chicago Tribune, Stillo entered a blind guilty plea, meaning he did not negotiate a plea agreement with prosecutors.

Stillo was accused of diverting at least 380 tons of asphalt from city to private projects in four months, and pocketed approximately $150 to $250 for each truckload, the Tribune reported.

Stillo will face up to two years in prison and fines of up to $30,000 when he is sentenced later this year. He is the 23rd person to plead guilty in the ongoing federal investigation. Six people still face charges in the case.