Originally by: Angela Rens
sorry I asked 
It's hard to find help here in the forums. The usual assortment of kids shouting "ha, ha, you're dumb" tend to drown out what little help does show up.
I'm not sure I can be any real help to you, as I've never hired a merc before (and probably wouldn't), but I imagine that the best way to go about it would be to post an offered bounty on the offending Orca which you will only after seeing an API verified kill mail. Personally, I'd ask the merc to kill the silly thing right in front of me as I was mining.
I also imagine the bounty would have to be fairly hefty. If that Orca is fitted for tanking it'll cost a bit of money to suicide him in highsec.
That being said, my real advice, assuming you mine regularly, is to find a good mining corp to join. One that can supply Orca support, pays you more than you can make solo, and can provide anti-flipper PvP support.