IRVING, TX – A police squad car had been inspected and allegedly fitted with used tires a few weeks before the vehicle slid out of control in severe weather, killing an Irving, Tex., police officer, according to the Dallas Morning News. But documents released to The Dallas Morning News after an open records request show that the city shop’s work order indicates billing for four new tires on the squad car during a checkup in late-March.

Worn tire treads may have been a factor in the mid-April death of Officer Andrew Esparza, and the rear tire treads were below minimum standards, police reports show. Irving officials have been investigating the accident and studying city vehicle maintenance policies. A police report on the accident said that it was “inaccurate” that new tires had been placed on the car.

Irving officials said they’re looking into the discrepancy.

City Manager Tommy Gonzalez has requested an internal audit of the city’s fleet maintenance department, according to the Dallas Morning News.

The work order also indicated that four new rims were put on Officer Esparza’s vehicle, which could raise questions about whether the discrepancy was a paperwork error.