P.S. Apart from above, the prof was in the programme because he was `advisor` to government on killers released from jail so knew all about the first murdered woman and the part of the second murdered woman, who had been monitoring her. I think we are to assume that second one was murdered because she wanted to spill the beans to all and sundry about the first murdered woman being a killer herself. That is why she went visiting woman and husband.
After thinking about it for two days, that is what I think happened so hope it makes sense