Could the Newtown shooter's estate be sued?

[HooptieWagon]

4. It will be difficult to prove.

You'd have to prove she knew her son was dangerous - difficult if he hadn't shown any previous signs of violence or intent. Then you'd have to prove she was negligent in the storage of the weapons based on her knowledge of her son's condition.
We don't know that she knew in advance the threat her son posed. We don't know to what extent she secured her guns. We don't know to what lengths the son went to access the guns. When that information is released, it's possible a case can be made...also possible a case can't be made.