Criminology - Stainer

[NSArebel]

There have been a rash of thefts in my school in the last year. My father, a chemist, put me onto the idea of placing an MP3 player, treated with a chemical that would stain hands or otherwise identify the thief, in hopes of the thief taking it and therefore, unwittingly, marking himself. Obviously, this stainer would need to remain on the skin for at least a week, provided no chemical cleaners are applied.

However, after a look on Google, it was suprisingly hard to find such a stainer. Does anyone know of one?

We have a chemistry lab, so if it's possible to mix this stain together manually, a description would come in handy.

[Borek]

Something visible in UV may be easier to find.

[JGK]

From Boichem classes and accidental exposure you may want to look at somthing like this

Nihydrin (http://en.wikipedia.org/wiki/Ninhydrin)

stains on direct contact and takes time to fade

[GCT]

So the idea here is that the students are going to be screened in some methodical way after the MP3 player has disappeared from a common theft spot? Here's a scenario

An individual who was not originally the culprit becomes tempted and eventually gets caught with the screening, news of this protocol spreads, and then those original culprits can merely modify their behavior and apply the right cleansing agents.

The students need to keep those devices to themselves, it is their fault ultimately if it gets stolen. Perhaps a candid camera approach is better. With the chemical approach the individual that got caught may simply claim that another student sold it to them, and things are going to get complicating.