The Count employs the infamous Italian bandit, Vampa. Why would a man of such wealth use a common criminal to do his bidding?

Well, ironically though criminals cannot be trusted, they have a mutual understanding and agreement. The count always pays well, just enough to keep it business and just that. When employing criminals there is a fine line, if you pay too little, they become greedy, if you pay too much they get comfortable and eventually want more.

That being said, it is not known, yet it could be assumed that The count has or could tip off Vampa about a rich shipment or etc. That is the mystery of the Count that we love, he knows the upper echolon as well as the underbellies. I think its a key to realizing just how deep the Count has planned his revenge.