I was sleeping in a makeshift tent in my car’s backseat while parked on campus (ahh, the joys of school!) when someone began trying to force my door open. Popped upright, pulling the blanket/tent down, stared at the guy for a second, while he went wide-eyed at having a human being suddenly appear in front of him. Then, he just took off running.
At my retail job, I catch people in the act at least once a week; according to store rules, I’m not supposed to do anything or accuse him; instead, I’m somehow supposed to get a member of management (usually involving going off to a phone to page them) AND never lose eye-contact with the “potential” thief from the point that I saw them pocket something to the point that they bypass both sets of front doors. Right. Instead, I just walk up when I see them do something and, without accusing them of stealing, say something like…
“Hi! Y’know, it’s usually not a good idea to put <item> in your pocket, since you might forget it’s there… mind if I take <item> up to the cashier for you, so you don’t forget?”
or
“Y’know, it’ll be really difficult for the cashier to check you out when you’ve removed the box/security tag to <item> and put it behind this merchandise; they might even gasp accuse you of stealing <item>, which would suck! Let’s take the item and box up to the cashier so you won’t forget to buy it!”
About 50% of the time, the would-be thief will realize they’re being given an easy out-- just pay for the item-- and the other 50% of the time, they feign ignorance: “oh, sorry, I put the item in my pocket accidentally, oops,” which allows me to give them an out by just saying “oh, yeah, haha, good thing you remembered it was there, that would be awkward otherwise! Did you want to purchase it, or shall I put it back on the shelf for you?”