A former college roommate of mine, with whom I lived for a semester over two years ago, was recently arrested for the murder of a young woman (whom he apparently stalked for quite some time), and I have been called to the police to testify as a witness, presumably to his character. Being in this situation, and being a bit philosophically inclined, I have been facing down a lot of questions in my mind, and I would like to hear your thoughts on them. First, and most abstractly: at the time, was I living with a future murderer, or with someone who had the seed of a murderer in him? Or was he just a regular person? Also, when I look back, I seem to remember him as a bothersome person without much respect for personal boundaries. I certainly didn't like him, and after a month or two I did my best to avoid getting caught in a conversation with him. But can I be sure this is what I really thought of him, and not a feeling I am projecting back onto those memories now that I know what he has done? Is it possible I am reshaping my discomfort from the time such that it fits his crime? Am I a reliable witness? Perhaps most importantly - if I had accepted his manner, which seemed irritating to me, and had been his friend despite our differences, perhaps he would have had more positive experiences, and would not have stalked and killed this young woman. Am I, in some diffuse way, responsible for his turning into a criminal? I am sorry for the mix of questions. These events have been a bit unsettling for me.