A Texas man pleaded guilty in federal court to smuggling a gun in connection to the March kidnapping of four Americans in Mexico, a federal prosecutor announced Wednesday.

Roberto Lugardo Moreno Jr., 42, of Harlingen, Texas, entered a guilty plea to charges of straw purchasing and smuggling a firearm for members of the Gulf Cartel, according to a statement from the Department of Justice.

An investigation revealed Moreno purchased a multi-caliber AR-style pistol at a pawn shop in Brownsville, Texas, in 2019, the Justice Department said. According to a federal complaint, Moreno lied on a form stating he was the buyer but later admitted that he purchased it for another person he knew was going to supply a Gulf Cartel member in Mexico.

“All too often, firearms are trafficked into Mexico where they end up in the hands of criminals who use them to murder, rob and extort innocent people,” U.S. Attorney Alamdar Hamdani said in a statement. “Moreno helped smuggle a firearm for criminals he knew were in the Gulf Cartel who then allegedly used it to murder and kidnap American citizens.”

Sentencing for Moreno was scheduled for Aug. 9. Moreno will remain in custody pending that hearing, the Justice Department said.

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The March 3 kidnapping occurred in Matamoros, Mexico, which is located just across the border from Brownsville. The four friends were assaulted and kidnapped shortly after crossing the border into the city of Matamoros.