To me, the part of this comment that smacks of empathy failure is where you say "That their daughter has died is very little excuse."

My original version (which I truncated because the comment was getting too large) was perhaps more clear. It explained that it is an excuse in a similar way to "he was abused as a child" is an excuse to abuse children when an adult. It kind of explains it a little and perhaps warrants a lesser punishment but it doesn't directly justify it. This is distinct from the more direct kind of excuse like "self defense", "they had been abusing me consistently" or "they killed my daughter and I was getting revenge" where the actual behaviour is closer to being the right thing to do in the circumstances.

The above was condensed into 'very little' because I sometimes manage to refrain from exploring all tangents.