slope. we didn't find any shotguns. >> police never find the weapons, but they do follow her next lead, and that is to the place where the guns were purchased. >> we went to san diego, the goal being we would check every buy book in the county or the town if we had to. >> they visited a lot of gun stores. this is just basic good detective work. they looked at the registers where people would buy guns. >> the second place was a big five. >> at first glance, it seemed like this was going to be yet another dead end. >> they didn't see the menendez boys' names in the register. they saw the name of a friend of the menendez boys. >> and the mossbergs. after that, it started coming together real well. >> the real question was how did