(CNN) -- A weapon that was used in the fatal attack on a U.S. immigration agent in Mexico originated in the United States, the Bureau of Alcohol, Tobacco, Firearms and Explosives said Tuesday.
ATF agents arrested three men in a Dallas suburb Monday in connection with the purchase of weapons that were smuggled into Mexico, the agency said in a news release.
U.S. Immigration and Customs Enforcement agent Jaime Zapata was killed and another agent injured when they were ambushed on a highway in the Mexican state of San Luis Potosi last month.
One of the weapons used by the drug cartel members who attacked the agents was purchased by one of the men arrested in Texas, the agency said.
Ranferi Osorio, 27, and his brother, Otilio Osorio, 22, were arrested at their home in Lancaster, Texas. Their next-door neighbor, Kelvin Morrison, 25, was also arrested. He is charged in a separate federal criminal complaint.
The trio were ordered by a judge to remain in custody pending a probable cause and detention hearing.
The Osorio brothers are each charged with possessing a firearm with an obliterated serial number, the ATF said. Morrison is charged with making false statements in connection with acquiring weapons and dealing them without a license.
Federal authorities had been tracking the Osorios' weapon trafficking activities before Zapata's killing in Mexico.
According to one of the affidavits filed in the case, in November, a confidential informant met with the brothers and accepted weapons from them. Authorities pulled the brothers over after the handoff, and found Morrison as a passenger in the vehicle, too.
The informant transported the weapons -- 40 in all, and all with the serial numbers obliterated -- to the border with Mexico, where authorities stopped him, the ATF said. Three of those weapons were traced back to Morrison.
In a separate action, Mexican authorities recovered the weapons used in Zapata's killing. One of those weapons was traced back to Otilio Osorio, who had purchased it in the Dallas/Fort Worth area in October, the ATF said.
"Ballistic testing conducted by Mexican authorities on this firearm indicated it was one of the three firearms used during the deadly assault on Special Agent Zapata's vehicle," the agency said.
If convicted, the penalty for possessing a firearm with an obliterated serial number is five years in prison and a $250,000 fine, per count. The penalty for knowingly making false statements in connection with the acquisition of firearms is 10 years in prison and a $250,000 fine, per count. The penalty for dealing in firearms without a license is five years in prison and a $250,000 fine, per count, the ATF said.
