Karen is responsible for Ben's death. She should have allowed him to decide of he wanted to visit the mother on his own accord. Of course since they are all "good characters" no one will say that to her directly even of she knows it, but she is. And neither did he hence sparing her and not mentioning she was the other person.
And is interesting, because ben seemd to always leave alone the relatives of the people he was investigating, and now, because of karen, he did involve a relative (Wilson's MOM) and he ended up dying for it
Wrong! The killer is responsible. Now if you want to place blame on a second individual then it’s all on Ben. He was a grown man and could have firmly said no I’m not getting involved in this. Don’t ever ask me again!! He chose to take part, he wasn’t physically forced so that’s all on him.