john alexander's shift at the beer 30 liquor store in marionville, missouri, starts out like any otheril an unfamiliar and suspicious customer walks through the door. and it's all caught on camera. >> about 9 -- between 9:00 and 9:30 at night. and i had a gentleman that came in, smoking a cigarette. and he had tattoos all over him and stuff. i asked the gentleman, i said, "sir, we don't allow smoking here in the store." i said, "can you please take your cigarette back outside." he just stood there, you know, starry eyed at me and took off puff off the cigarette. >> alexander begins to think he might have a major problem on his hands. >> just the look on him, looking dead in my eyes, and i can tell he's not hearing what i'm saying. what he's trying to do is trying to psych himself up to do what he's come in there to do. >> alexander tries to remain calm, allowing the customer, whose name he later learns is arvin brandon smith, to make the next move. >> as soon as he put his cigarette down, he reached down, pulled his gun up, and of telling me, "you need to give me all your f'ing money."