yah...I read that 44 page report when it came out, and it was significant for what it did not say moreso than for what it did. In my opinion, and based on my understanding of the report itself, I think it is clear that Nancy Lanza significantly contributed to this massacre by not only ignoring some very obvious problems with her son, but by trying to deal with those problems by buying him firearms. One of the pieces of evidence seized from her home was a Christmas check made out to her son for a new semi-automatic pistol.
The report does not blame her directly, but I believe had she not been the first victim of her maniac son, Nancy Lanza would have been prosecuted as an accessory to each and every one of those murders. Time will tell if Dad is ever sued for his potential liability in any of this.