Your best source of info will be any local REALTOR. Please do NOT rely on these sites (Trulia, Zillow, Realtor.com, or any other website) for ANY accurate listing info. These are just marketing sites and a way for them to generate $$ from us agents and lenders. The data is terribly outdated and inaccurate.
Your Realtor will be able to search the local MLS which is your ONLY place to find the most up to date listings. The reason why it's "Off Market" is likely because it was under contract and then sold. This site will never show a property as being under contract. Why do they do this? So they can charge us agents for "leads" from buyers like you. They want it to appear that there are lots of properties available, so there are lots of leads generated for us. Good luck to you!