The defense needs to show that she was in/or the opportunity was there for her to have been in the MH prior to 2/1
If the victim had not known the accused and had not been in his environment before...that is pretty good circumstantial evidence to me...but that is not the case here.
THey do matter, but the question still is when did they get there. That would be the crux of the situation. If they got there after 1030pm Friday 02/01/02, DW looks GUILTY.