UF’s Science Library is open until 1am (2am during finals week)
Our Engineering computer Lab was 24/7, and no matter the time there were always people there.
My comment wasn’t about the fact that the library was open at 12:30am. It was that the shooter chose to go there at 12:30am rather than say anytime after sunset when more people were there. Which makes it seem like short of the shooter have huge mental issues (definitely possible), he was there to single out a specific person or two.