How do I know if the person on the other end is legit?

[Dominique Pratt]

I have a buyer in the Bay Area and I agreed to JV on some deals in LA.

I trust that my Bay Area buyer is legit but how do I know if the person I JV with is legit. I found them through an investors group on FB including my buyer but I don't know how to be sure they won't take the information I have on my properties and run off with them? This could potentially be my first deal and unfortunately I have no mentor to run it by just to make sure my ducks are in a row.