> "doing searches for credit cards"
Is there an easy answer to "how on Earth?"
PIs and law enforcement can get access to credit card information in any of a number of ways, some more legal than others. Social engineering, digging through credit card receipts, impersonating the person who owns the credit card ("pretexting"--which wasn't illegal until recently), and so on are all common, at least according to a PI mailing list a friend of mine belongs to. Fascinating stuff.