How can I find out if home is being sold by wholesaler?

[Jovan O.]

I'm a newbie starting out as a wholesaler.  I'm searching through "For Sale by Owner" properties and a lot of these sound like the home is being advertised by someone other than the owner.  My question is for other wholesalers....how do you know or what is a good way to find out if the home is under contract already?  Are there specific questions I should ask or just be blunt about it?