A pistol, drum magazine, two additional magazines and a ballistic vest that an undercover agent with the U.S. Bureau of Alcohol, Tobacco, Firearms & Explosives said she purchased from Oscar Gil-Izquierdo of Chicago. The Chicago man is in federal custody. (ATF photo)

A Chicago man has been charged with trafficking a firearm.

Oscar Gil-Izquierdo sold a Radical Firearms Model RF-15, Multi-Caliber AR-pistol, drum magazine, two additional magazines and a ballistic vest to a buyer on Thursday, according to a criminal complaint filed in U.S. District Court in Chicago.

The transaction occurred in a parking lot on the Southwest Side of Chicago, the complaint states.

Unbeknownst to Gil-Izquierdo, the individual to whom he sold the gun and other items was an undercover agent with the U.S. Bureau of Alcohol, Tobacco, Firearms & Explosives, according to the complaint.

Gil-Izquierdo, 25, is charged with attempting to transfer a firearm to a person he knew could not legally possess it. The undercover agent had informed Gil-Izquierdo that she was a convicted felon and could not legally purchase a firearm, the complaint states.

On Monday, U.S. Magistrate Judge Gabriel Fuentes ordered Gil-Izquierdo detained in federal custody without bond.

The Chicago Field Division of the U.S. Drug Enforcement Administration and U.S. Immigration and Custom Enforcement provided assistance in the case.

If convicted, Gil-Izquierdo faces up to 15 years in federal prison.

Gil-Izquierdo sold the gun and magazines to the agent for $1,400 and the vest for $600, according to the ATF. The agent also paid the Chicago man $200 for travel expenses, according to the complaint.

ATF agents said Gil-Izquierdo admitted to selling the undercover agent the items and that he knew it was illegal for felons to possess firearms.

One agent said when contacting Gil-Izquierdo about a “toy for sale,” he replied, “Yes, a short r (AR-pistol).”

Gil-Izquierdo texted photos of the gun, magazine and vest, according to the agent.

The suspect went to an Archer Avenue parking lot and got into a vehicle with a second ATF agent who posed as the first agent’s girlfriend, according to the complaint. He brought the vest and a duffle bag with him, according to the complaint.

The duffle bag contained the gun and magazines, the second agent stated.

That agent said she told Gil-Izquierdo that she wanted that type of gun, but that she could not buy it at a gun store because she was a convicted felon.

After the money was exchanged, Gil-Izquierdo was placed under arrest, the complaint states.

kbeese@chronicleillinois.com