In this 2016 file photo, U.S. Customs and Border Protection officer R. Hernandez uses a density-measuring device on a Mexico-bound vehicle.

Mike Christy / Arizona Daily Star

A foiled gun-smuggling attempt in Nogales, Arizona, and a daring raid at an airstrip in Sinaloa, Mexico, led U.S. authorities to a gun shop on Tucson’s northwest side.

Along the way, federal agents encountered rifles powerful enough to take down a helicopter, two phony home invasions, dozens of fraudulent gun sale records, and a former Tucson police officer accused of stealing the identities of people he arrested as part of a scheme to smuggle guns across the border.

Joe Santiago Valles, a Tucson police officer from 2012 to 2014, was sentenced July 6 in U.S. District Court in Tucson to 6½ years in federal prison after pleading guilty to 30 counts of falsifying federal firearm records, identity theft and witness tampering. The prosecution of alleged co-conspirator Timothy Veninga, who was a federally licensed firearms dealer, is ongoing.

The investigation of Valles, 34, and Veninga, 48, began in March 2016 when U.S. Customs and Border Protection officers in Nogales caught a man trying to smuggle a Kel-Tec PMR-30 pistol into Mexico, according to court documents and testimony at the July 6 sentencing hearing.

Although the pistol’s serial number was obliterated and painted over, federal authorities were able to recover the number and trace the gun back to a sale the day before at Ballistic Firearms, which Veninga ran out of his house in the 3400 block of West Marlene Street. Valles ran a gun-painting business out of the same house.

When federal agents checked records at the shop, they found something odd: The names of Valles’ relatives appeared repeatedly in the forms required for gun sales by the Bureau of Alcohol, Tobacco, Firearms and Explosives.

“Every family member had a .50 cal,” ATF Special Agent Chris Bort testified at the Thursday sentencing hearing, which he called a “huge red flag” indicating gun smuggling.

One Barrett .50-caliber rifle — a model Bort said was favored by drug cartels and had been used to shoot down law enforcement helicopters in Mexico — traced to Ballistic Firearms was seized by the Mexican military in September at an airstrip in Culiacan, Sinaloa.

The raid at the airstrip was set in motion by the arrest of a man with three guns earlier that day in the border town of Mexicali, according to Rio Doce, a Culiacan-based newspaper. The Mexican military discovered a delivery was to be made and headed to the airstrip.

The pilot of the Cessna saw the military approach and tried to take off, but the driver of a Mexican military truck drove into one of the plane’s wings to disable it, the newspaper reported. In addition to the .50-caliber rifle, the military seized four AK-47 rifles.

As was the case with the Nogales bust, the serial number of the Barrett .50-caliber rifle seized at the airstrip was destroyed and painted over, Bort said. But an ATF attaché in Mexico took photos of the rifle, which were used to trace it back to a Tucson man who supposedly bought the gun at Ballistic Firearms.

The ATF routinely traces guns seized in Mexico to sellers in the United States, including 120,000 from 2007-2015, according to annual reports from the ATF’s International Firearms Tracing System.

However, the only connection the Tucson man had with Ballistic Firearms was that Valles had arrested him in late 2014 for a DUI violation, according to court records. ATF agents found records from the DUI arrest, which contained the man’s date of birth and other information required for ATF forms, when they searched Valles’ house.

When authorities tracked down the man, who was not charged in the smuggling scheme, he burst out laughing at the idea he could afford an $8,000 rifle, court records show. He told agents he pays his bills by selling plasma and receiving child-support payments.

Another man whose name appeared on more than two-dozen sales records was arrested by Valles, who kept the man’s personal information. Arizona courts declared him mentally incompetent, federal prosecutor Serra Tsethlikai said at the sentencing hearing. He lives with his mother and is allowed to carry only enough money to cover his bus fare.

Bort testified Valles’ brother told authorities the money to buy the guns came from an unknown individual Valles met on more than one occasion in a parking lot.

Only one of the firearms was recovered by U.S. authorities, and Judge James A. Soto ordered Valles to pay $62,000 as part of a forfeiture complaint for 31 firearms.

Those guns, which were sold from October 2015 to March 2016, are “the tip of the iceberg,” Tsethlikai said. “We can only guess how many firearms made it to Mexico.”

Soon after the ATF inquired about gun sales, the defendants staged two “fake home invasions” and destroyed the rest of the sales records, she said. Not only did investigators lose valuable information, but two people who matched the phony description Valles and Veninga gave to sheriff’s deputies ended up facing deputies with drawn guns, she said. They were on their way to a Sonic restaurant.

However, agents were so “shocked” during their visit to the gun shop they took “covert photos” of records, Bort said. Agents determined Valles recruited his brother, sister, and sister’s boyfriend to sign ATF forms saying they bought the guns. Valles paid them a few hundred dollars for each form they signed.

After ATF agents interviewed the family members, who were not charged, one of them agreed to wear an electronic listening device and meet with Valles, court records show.

During the recorded meeting at a Tucson apartment complex, Valles told them to not cooperate with law enforcement and said the guns were “out of the country.” He also said he “got rid of all the paperwork,” court records show.

Assistant public defender James Smith claimed prosecutors were trying to “elicit the boogeyman of cartel violence in Mexico” but could not prove Valles was involved in gun smuggling.

Smith also questioned the validity of the recorded conversation, which was made months after the Nogales bust. Valles had no way of knowing where the guns went, Smith said.

Smith referenced a recent gun-smuggling case in which four residents of Sahuarita and Green Valley were indicted in 2015 for smuggling guns disguised as metal artwork to Hong Kong. One of them was sentenced in April to 8½ years in prison.

That case included charges of gun smuggling and money laundering, which Smith noted were not filed against Valles. Instead, Smith argued his client only violated laws regarding ATF forms.

“So, you’re telling me this is a forms case and not a guns case?” Judge Soto asked Smith. “You’re going to have a hard time convincing me of that.”

However, Soto denied Tsethlikai’s request for an increase in sentencing due to a connection with gun trafficking, saying the prosecution had shown Valles knew the guns were headed to Mexico but had not presented enough evidence to show he knew the guns were going to cartels.

Valles resigned from TPD in December 2014 after two accusations of lying on police reports, according to records from the Arizona Peace Officer Standards and Training Board. He did not admit guilt, but he permanently relinquished his certification as a peace officer in Arizona in May 2015.

Contact reporter Curt Prendergast at 573-4224 or cprendergast@tucson.com