Well, that got me thinking.
I don’t think you can buy the ink packets as a private citizen, and apparently they can cause bodily harm since they explode…don’t want to be sued by some scumbag after they steal from me. They’re also radio controlled/tripped, so it’s a bit of a set up.
They make pepper spray traps/trips, but since pepper spray is illegal in DC without a permit, that’s a no go.
Most theif powders are florescent, HOWEVER, some are visibile: http://bit.ly/ZmcNKk is a powder, http://bit.ly/123FShR is a liquid. One option would be to dust the object, like it suggests. Another would be to fill the inside of the bag/package with some of it, so it gets EVERYWHERE when they open it.