St. Louis, MO (KTRS) A St. Louis man is facing federal firearms charges after he allegedly robbed an undercover police officer who was working as part of Operation Legend.

The U.S. Attorney’s office says that 22-year-old Dariyon Martin was charged Friday with being a felon in possession of a firearm, robbery, and brandishing a firearm.

According to the criminal complaint, an undercover St. Charles Police Detective arranged to buy a gun from Martin back on August 7th. After Martin entered the detective’s vehicle, he handed him a gun. But when the detective reached for the money to pay for the gun, a struggle ensued, and Martin took both the gun and the money.