It started as a routine traffic stop.
When Jace Allan Tornio fled his vehicle after being pulled over last April, however, police found he was transporting a fearsome arsenal.
He had a “Glock-style” pistol without a serial number, several rounds of ammunition and a device that enabled guns to be converted from semi to fully automatic.
That was just the aperitif: when police searched his home in Escondido, California, they uncovered a gun-making factory.
Inside his vehicle were gun parts, ammunition and a pair of 3D printers used to make “ghost guns” – so called because they are untraceable.
Tornio was sentenced to a year in jail this week, the discovery of his gun factory laying bare the epidemic of home-made guns.
Traditionally, ghost guns were made from components that are not regulated by federal law. The parts, which account for about 80 per cent of the weapons, are made from aluminium or polymer.
However, according to the National Police Foundation, the landscape has changed. As demonstrated by Tornio, 3D-printing technology has made it possible to produce working guns from plans that can be found easily online.
According to one estimate, about 100 companies sell gun kits and parts.
Because dealers were selling “parts”, buyers were not subject to the normal array of background checks. It meant the kits could be bought by criminals, the mentally ill and even children.
The results have been devastating.
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In Georgia, for example, a 13-year-old boy killed his 14-year-old sister after accidentally shooting her with a gun he had made at home.
US President Joe Biden moved to close the loophole in April last year, banning the manufacture of ghost-gun kits that can be assembled in as little as 30 minutes.
He had bipartisan support for the rule outlawing home-made firearms but a Texas court in July ruled the ban was unconstitutional.
The Supreme Court on Tuesday ruled that the Biden administration's regulations can temporarily take effect during the ongoing appeals process.
Ghost guns have been the weapon of choice for many criminals.
According to figures compiled by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), the number of ghost guns recovered by the police increased by more than 1,000 per cent between 2017 and 2021.
The weapons have been used in at least three mass shootings in California in the past decade. Local politicians have acted ahead of federal action.
Los Angeles changed its municipal code to ban them and the move has been effective, Det Patrick Hoffman of LA Police told The National.
“We began monitoring ghost guns in 2020,” he said.
“We began seeing an increase in the recovery citywide. There were 813 recovered in 2020 and 1,921 in 2021, which was a pretty significant increase. Then in 2022, we recovered 1,706.
“Thus far in 2023, we are down significantly. A lot of that is to do with enforcement efforts and the publicity ghost guns have garnered in the news media.”
Joe Biden unveils new rule to fight against so-called ghost guns – video
Det Hoffman added: “In the city of LA, we drafted and enacted the municipal code in April last year to directly deal with ghost guns and unserialised firearm parts. It assisted in our enforcement efforts.
“Before that, firearm parts were not considered a weapon. They were just parts which meant they could be ordered by people who would otherwise have been prohibited.”
LA police and several federal agencies, including the FBI, the Department of Homeland Security and the ATF are going after ghost-gun makers.
“There are several task forces and we are targeting our efforts on the actual distributors, working our way up the chain,” Det Hoffman said.
“The homicide rate is down significantly. We are making an impact on firearms and it does have an impact on homicides, we are down 22 per cent compared to last year.
“These legislative changes have had a big impact.”
California has followed Los Angeles's example, with a bill being steered through the state legislature by Democratic Assemblyman Mike Gipson.
“I’m proud to have been particularly active in this fight against untraceable firearms known as ghost guns,” he said.
“Regardless of what happens in Washington, DC, California’s will to stop the scourge of violent gun proliferation will stay firm.
“I expect our efforts on gun control to be met with resistance from outside forces but there is broad support in my state for sensible control of ghost guns as they are the tool of choice for the most violent, lawless actors.”
In Washington, Mr Biden has strong support for combating the problem from senators such as New York Democrat Kirsten Gillibrand.
“Let me be clear, we aren’t talking about water pistols here,” she said when introducing a bill to ban online blueprints for ghost guns.
“We’re talking about real and fully operational semi-automatic firearms, like AR-15 style rifles and Beretta 9mm handguns.
“Because many of the 3D-printed guns are made of plastic, they can bypass metal detectors commonly used in courthouses, airports and other secured public areas.”
She said those who should not have access to guns should not be able to print one.
“By cracking down on the blueprints as well as the guns themselves, we can limit the general availability of ghost guns and make it more difficult for dangerous individuals to get their hands on them,” Ms Gillibrand added.