By Sarah Kinosian and Laura Gottesdiener
MONTERREY (Reuters) - * A former investigator for the U.S. Bureau of Alcohol,Tobacco, Firearms and Explosives (ATF) is accused of smugglingguns into Mexico while employed by the agency in 2017, accordingto a letter sent to ATF's head this week by U.S. Senator CharlesGrassley.
Jose Luis Meneses, a Mexican national who worked as an investigator for ATF at the U.S. Consulate in Tijuana, admitted to buying firearm parts online and at a California gun store and trafficking them into Mexico for profit back in 2017, according to the letter and an ATF memo from the time obtained by Reuters.
The case has not been previously reported.
The trafficking of U.S. weapons south across the border is a top diplomatic issue in Mexico. Mexican officials accuse their American counterparts of not doing enough to stanch the illegal flow of these guns, which they say help arm drug cartels and contribute to the country's high homicide rate.
Nearly 70% of traced firearms used to commit crimes and seized in Mexico come from the United States, according to ATF.
The Grassley letter dated Oct. 18, which cites the 2017 ATF memo and information described as "whistleblower disclosures," accused the agency of not conducting a full investigation into the matter.
"If these protected disclosures are true and accurate, they illustrate a failure by the ATF to hold its employees accountable for criminal misconduct."
Grassley's letter also raised questions about how much information U.S. officials told their Mexican counterparts about the allegations of gun smuggling by the ATF employee, a point that could stoke tensions between the two countries.
A senior Mexican diplomatic official called for an investigation.
"We will demand they get to the bottom of this in order to bring those responsible to justice and that this type of action never happens again," the official said.
ATF confirmed it had received the letter and said the agency investigates such allegations and takes appropriate action, declining to discuss details of the case.
A U.S. government official said that's what happened in this case.
"The embassy found out about suspicious activity, revoked compound access within a day, did an investigation, and fired him within a month. It's terrible that it happened, but this is exactly how it's supposed to work," the official said.
The U.S. government "has no tolerance for that sort of behavior," he added.
The internal investigation into Meneses began when a firearm parts vendor called the U.S. Consulate in Tijuana to report suspicious purchases, according to Grassley's letter.
The tip led U.S. officials to interrogate Meneses, who admitted to buying firearm parts in the U.S., smuggling them into Mexico and handing them off to his brother, a Mexican police officer, and a former Mexican soldier, according to the ATF memo.
ATF agents from the San Diego office then searched the post office box that Meneses said he used for the purchases, where they found assault-style rifle parts and high-capacity magazines, the memo said.
Meneses used a vehicle with diplomatic plates to avoid being searched at the border while smuggling the firearms, according to the letter. In total, Meneses said he bought enough parts to assemble eight AR-15 rifles, the memo said.
Meneses was placed on administrative leave and then terminated in April 2017, the memo said.
In Grassley's letter, he accused the agency of treating the allegations of gun smuggling like an "administrative matter" and questioned whether ATF investigated possible links between Meneses or his associates and Mexican cartels.
The ATF memo is a detailed summary of Meneses' case prepared by a top ATF official in Mexico at the time, and addressed to the then-head of Mexico's specialized unit to investigate cases of terrorism and arms trafficking.
But it's unclear whether the memo was ever sent.
On May 9, 2017, the ATF official sent an email to a top State Department official in Mexico saying that "ATF will not make any notifications to GOM (the government of Mexico)."
Neither ATF nor the Mexican government responded to questions about whether U.S. officials later informed Mexico about the case. Reuters was not able to contact Meneses.
ATF's activities in Mexico have sparked controversy in the past. From 2009 to 2011, a once-secret ATF scheme, known as "Fast and Furious," set out to thwart U.S.-Mexico gun smuggling by allowing people to illegally buy arms in the United States and take them to Mexico so that the weapons could be tracked and lead law enforcement officials to drug cartel leaders.
But some of the weapons were later blamed for murders in Mexico and set off bitter cross-border recriminations over the gun-running scandal, which continues to reverberate in Mexico's politics over a decade later.