I don't know, why bother making murder illegal? Just sentence people who commit it. It kinda has to be a low to justify firing them for that reason, just as you'd kinda need to specify that murder was illegal to have any legal right to punish somebody for it... unless of course you carried out that ounishment by murder... which wouldn't be illegal in that scenario... ok, maybe not the BEST analogy, but you get the idea.

As for computer checks, to be perfectly honest, a place could probably get away with that if they made a big enough deal of it, or had experiences with the problem in the past to use to jutsify it in court.