I have heard him talk about this incident before. He always talks about it with decorum. I watched the whole interview. He does not vary in any suspicious way from his baseline behavior when he is asked about the event. He does not evade the questions concerning the incident.
In this interview he does talk about it gently as an “accident” and he truly feels it was. His eyebrows go up and he is truly expressive at one point.
He does not seem overly rehearsed. He seems to me to behave as a gentleman who has dealt with his grief and has had to answer probing questions about this event for years. It has been many many years since what we call in deception detection the “event.”
It is appropriate that he is not overly emotionally about it so that should not be misinterpreted as any indication that he is in any way guilty.
Below is the link to the interview.