Santa Monica police said Thursday that the man who went on a shooting rampage that killed five people last week built the semiautomatic rifle he used in the attack using components he purchased from various sources across the country.
The AR-15-style gun 23-year-old John Zawahri ended up with is illegal in California, but it wasn't registered because it consisted of a lower receiver — the base of the gun that contains its key mechanics and legally qualifies it as a firearm— that was only 80% complete and not considered a full weapon.
To buy a fully completed lower receiver, you'd need to pass a background check, but you can get a partially built "80% receiver"without one. For these receivers, you need special tools to turn them into firearms. Weapons built with these partially completed receivers aren't required to have serial numbers that would allow law enforcement to track them.
It's unclear how exactly Zawahri obtained the components to make the gun he used, but it seems relatively easy to find parts kits that are completely legal.
Zawahri had tried to buy a gun in 2011 and was denied for unknown reasons by the state's Department of Justice, The Los Angeles Times reports.
Zawahri also had a known fascination with weapons and had talked before about hurting people at school. Police had previously searched his house for bomb-making materials.
Mother Jones wrote this first-hand account of a "build party" showing how easy it is to build assault weapons from parts kits. 3D printing technology is also offering another way to build untraceable weapons— one New York City councilman is already planning to introduce a bill that would regulate weapons made with 3D printers.
Police are now investigating how Zawahri obtained the parts he used to make the gun used in the shooting.