Thanks for the photo. I am guessing they removed the bench rather than it evaporated into thin air.
Yes, they removed it and then OU workers replaced it within hours of the removal of the crime scene tape. As I said up in a post I mis-addressed, I'm pretty sure I saw another picture that showed marks on the sidewalk itself. At the time this photo was taken they also took pictures of people hosing down the buses parked nearby. My guess is that this picture was taken after they hosed down the sidewalk as well... again you can probably imagine why this was done. If I find the other picture I'll try to post it here or link to it.