Buying Bank own Properties NOT Listed for Sale

[Juan S.]

Hows it going BP,

While driving through an area of town where I would like to invest (Diving for $$) I came across a ton of properties in really REALLY nice neighborhoods that seemed to be abandon. You know the typical signs to look for over grown grass, tons of newspapers sitting in the driveway, weeds growing over windows, just signs that scream my owners don't care about me, one house even had a few meteor sized holes in the roof. I took note of these properties and spoke with a few home owners about the houses and many say that the houses has been vacant for years.. 

I do my research and find out that most of the homes have been foreclosed on and the bank on county records are listed as the owner. The bank as been listed as the owner for a couple of years now on some while others where listed as the owner within the last six months to a year but not listed for sale. 

My question is can it be possible to purchase these properties although they are not listed for sale and how would someone go about doing that? Is there any typical reasons why the bank as not listed them for sale?