Here are some of my simple defenses for such things:
1) Merchants hire low level Mentalists to simply cast "Presence" to guard a place. Like hiring out a town guard to "guard" something.
2) Magic weaved into the structures (but only higher end ones) like the wards mentioned in Castles and Ruins...
3) Illusion and mind speech spells used to communicate with people within a fortified structure (like a bank) that way there are no "real" people to attack LOL just illusions and voices in the PC's heads!
4) Have low level magicians cast invisibility on a heavy crossbowman/tank in the corner of a shop, sitting, waiting there for something to happen... this is just like having someone guard a "post" all night... and remember, invisibility (or Unseen) lasts for 24 hours
5) Another really NASTY town merchant trick is to have a ward on large cash reserves... in a vault. The wards dont activate until some trigger inside (which was set by the merchant when they left hte vault)... then when the trigger even happens (say touching of money,gems,items other than the merchant) the wards "arm" and dont allow anyone to escape...preventing spell casting through them or alltogether.
Now THAT is fun watching how the party deteorates once they are caught by something like that... I have never SEEN such backstabbing! LOL! The old scenario that you let the thieves in, but you dont let them out!
If a crime has already taken place:
1) Ranger tracking spells
2) Dabbler tracking spells used in conjunction with Intuitions and Rangers lists (massive combo)
3) Seer's spells ? ?Past Visions? are AWESOME for this?
4) Scrying spells
5) Open Mentalism ? Delving ?Deaths Memory? for tracking down or identifying the killer of a merchant, shop owner, peasant, noble or public official (guard)? I use this spell only in big cities because most small towns wouldn?t have someone 15th level hanging out to cast it within 24 hours.
Also, in the RM Companion III three is the ?Sleuth? class. Might want to dig up this info and use it ïŠ a class specifically designed to ?hunt? people down.
Check out this post, it?s for when someone or a witness is interrogated?
http://www.ironcrown.com/ICEforums/index.php?topic=4900.msg71313#msg71313
1) Soul Destruction ? Essence ? Question ? 1st
2) Mind Merge ? Mentalist ? Read Emotions ? 2nd
3) Mind Merge ? Mentalist ? Thoughts
4) Mind Control ? Mentalist ? Question ? 1st
5) Mind control ? Mentalist ? Charm Kind 3rd
6) Spirit Mastery ? Essence ? Charm Kind 2nd
7) Spirit Mastery ? Essence ? Suggestion 5th
Just to name a few?