ST. LOUIS (KMOX) – A former St. Louis police officer admitted to authorities that he bought heroin while on duty and even chauffeured a drug dealer around the city.

Jason Stewart, 31, pleaded guilty on Wednesday to being a drug addict in possession of a firearm, highlighted by his driving heroin dealers around and buying heroin in known drug areas of the city.

On Oct. 4, Stewart, who was on duty at the time as a deputy for the sheriff’s office, drove up to an area of the city known for drug trading. According to the plea agreement, the area was being watched by a federal and local surveillance team. At the time, Stewart was conducting a transaction before being pulled over by authorities.

When searching his car, investigators would find .17 grams of heroin as well as a bottle of urine wrapped in a hand warmer concealed in his pants, Assistant U.S. Attorney Hal Goldsmith told the court, according to the plea. Stewart later told investigators that he carried the bottle of urine with him as a means of protection for the drug tests at work. Investigators would also find drug paraphernalia in the car, soon discovering that Stewart was armed with a .38-caliber revolver.

Stewart admitted to police that he had been a steady heroin user for about three years, and that he had driven “at least one heroin dealer” around town in exchange for drugs while he was still on duty, according to the plea.

Goldsmith told KMOX that Stewart’s maximum sentencing could be up to 10 years in prison. But the St. Louis Post-Dispatch reports that Stewart is looking at between 18 to 30 months, the prosecution arguing that Stewart abused a position of trust.