The FBI says the San Mateo County Sheriff sergeant serves on their Joint Terrorism Task Force but the weapons and ammo were not FBI issued.
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The San Francisco Police Department is not talking on camera or releasing any new information as the investigation continues.
The San Mateo County Sheriff's spokesman says the department policy requires all weapons be secured to a fixed object and locked in some sort of way in the vehicle.
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A state law passed in 2016 requires all citizens and law enforcement officers to lock and secure all handguns inside a vehicle. Long guns and rifles, like the ones in this case, are exempt.
This is one of six thefts of law enforcement vehicles in the Bay Area since 2015.
The weapon used to kill 32-year-old Kate Steinle on Pier 14 was stolen from a Bureau of Land Management ranger's car in San Francisco.