By Bud Gillett, CBS 11 News

JOSHUA (CBSDFW.COM) – The gun used to kill a federal agent in Mexico on Feb. 15 was purchased legally from a company in Joshua, according to information released by federal officials Tuesday.

It’s “a horrible, tragic thing,” says Jim Terrill, whose business, Off-Duty Armory, sold a Romanian-made Draco 7-62 lat a Fort Worth gun show last October.

Federal officials now say it was one of three weapons used in the ambush killing of U.S Immigration and Customs Enforcement agent Jaime Zapata and the wounding of his co-worker last month in Mexico.

Terrill said he had no way of knowing it could later be passed on to someone affiliated with a drug cartel to kill a federal officer.

“Obviously, we grieve and we get outraged when things like this happen, especially to law enforcement,” he said.

Terrill says the armory is owned by people active in public safety themselves.

According to the U.S District Attorney’s office, 22-year-old Otilio Osorio of Lancaster, who was in court briefly Tuesday on a separate charge, bought the gun.

Terrill said Osorio provided him with a picture ID and the required background information – all of which was legitimate – and that the FBI did a background check and approved the sale.

“We sell tools here that are used for good things that can also be used for bad things from time to time,” he said, shaking his head ruefully.

Osorio and a neighbor, Kelvin Leon Morrison, also of Lancaster, had cases against them put off until Friday. They were arrested in Lancaster Monday during a raid.

Morrison is charged with illegally dealing firearms and lying about buying them; he’s believed to have sold them to drug dealers.

Court documents say Osorio and his older brother, Ranferi, possessed dozens of guns with serial numbers filed off that were destined for the violent Zetas drug cartel in Mexico.

However, none of the three have been formally charged in connection with Zapata’s death.

On Friday, all three will have detention and probable cause hearings before a federal judge. Federal affidavits say the Osarios admitted both to modifying and selling firearms they bought, and that Morrison made as little as $50 on firearms he allegedly sold.

Meantime, Terrill claims he and his co-workers do everything they can, even going beyond federal guidelines, to try to keep dangerous firearms out of the wrong hands.

“We don’t want firearms being put in the hands of people that don’t have any business with them – ever,” he said.