The investigation into how a 16-year-old student at Saugus High School obtained the 45-caliber pistol used in Thursday's school murders and shooting has become more complicated, as the handgun found at the scene appears to have been modified from its original form, several law enforcement sources told NBC News.
"We know the make and the model," LA County Sheriff Alex Villanueva told NBC's Miguel Almaguer. "We're not going to release that information until they do their complete analysis of the firearm itself. All we can release right now, is we know it's a 45, we're going through it, our firearms experts are going through it, and we're being assisted by the ATF."
The handgun may have been purchased in one form and had a cosmetic feature or barrel changed, the sources said.
Numerous other firearms were found during a search of the home where the 16-year-old Saugus High School attacker lived, including assault weapons and handguns. Law enforcement officials said they were also investigating whether the teen had unlawful access to the weaponry.
ATF agents said they had traced the histories of six other firearms found at the teenager's home, and Villanueva said investigators had accounted for a number of guns once registered to the teen's father, most of which were seized by the Sheriff's Department several years ago.
Villanueva said there were also weapons that were not registered to the father. "Some of the firearms were not registered at all."
Law enforcement sources familiar with the investigation told NBC4 Thursday guns and gun parts were found in several different areas of the home. A box truck was brought to the home by LA County Sheriff's deputies to transport the weapons and other evidence.
The guns taken from the family's home several years ago were destroyed, the sources said. The seizure followed an incident which led to the father undergoing a mental health evaluation, they said.