After a few seconds, John pointed the gun at the Library Tower / US Bank Building, which is the tallest building in Los Angeles. The building was .75 miles (a little over 1 km) from our position.Link (via MAKE Blog)
As more Bluetooth devices started appearing, John said, "This building is full of Bluetooth! Look we got some Blackberries!" He also explained that, with multiple guns, it would be possible to track a single Bluetooth device as the person walked around. In less than a few minutes, twenty devices were detected–all at distances over a half mile away! We decided to quickly conclude the scan, given police activity in the area earlier in the day from a bomb scare.