First of all, I drink wine from a box. If you check it out, most brands in boxes are actually less alcohol then bottles. Just because she bought a box, does not mean she drank the whole thing. I think we are too quick to accuse sometimes. It was posted earlier too by a local that it could of been her brother, Steve, with her at the store.
I'm not saying she is innocent, but just because she went to the store and bought a box of wine, does not make her a murdererer. Also, if her husband worked until 4am, I would assume he left for work around 7 or 8pm. That means he was home when she went to the store.
I personally like the boxes as you can have a glass and it doesn't go stale like an open bottle does. A box can last a couple of weeks!