[Avodah] May I purchase chametz after Pesach from any non-Jewish owned store?

[Prof. Levine]

Zev Zero wrote:

> > Therefore, when determining where to shop after Pesach, it is not
> > sufficient to establish that the owners of a store are not Jewish; one
> > must also investigate who supplies /chametz/ to the store as well.
>
>Why must one do so?  Where does such an obligation come from?  Having
>determined that the seller is not Jewish, what is the basis for
>requiring one to ask any further questions?   Im kein ein ladavar sof.

My son's Rav holds that indeed ein la davar sof.  He buys enough 
flour shortly before Pesach time to last him until the next 
Pesach.  He will not eat anything made from flour that does not come 
from his home.  He will not drink any liquor that was made from 
possible chometz, even if the liquor comes from someone who has sold 
their chometz.  When I asked him about this regarding liquor, he 
replied, "Who knows where it has come from?"

For the record, he is a "GRAnick".

YL