I think that you can do it with 2 of 3 Multisig address.
You will still need a 3rd, trustworthy person, but that person will have only to provide his public key and if anything goes wrong, that person can do the arbitrage.
I've seen on reddit some sort of tutorial for this, but it's for DOGECOIN.
The same principle works for Bitcoin too, but you have to study it more.
Of course, you still need a 3rd person. It's not really escrow, since the Bitcoin doesn't arrive to his wallet, but you need him in case of troubles.
Verifying a person you don't know is difficult. You can somehow verify a bitcointalk
account based on the trust feedback it has, but basically that's it. Unless you want to hire private investigators, of course