Milo cut the section of tape he needed because he never thought anyone would ever notice it. Milo locks the locker because he is in a hurry. He has to get out of the gym and home to establish his alibi. He is thinking like a man in a hurry, not like a man alone in an empty building. He should have put himself in his victim's shoes.

Joe

Too funny, putting himself in Stafford's shoes. But we also know that stafford was in fact left handed, so the shoe tying evidence probably would not wash. "Cass" can confirm this one I'm sure.

...but then he might have left even MORE scuff marks.

oh yes...gene stafford was definitely left-handed fred..we see that in that early scene.
i have always wondered how they (writers, director..etc..)goofed like that. the whole theory about the tying of the shoes goes right out the window...because we know he is left-handed. and wouldn't milo have known that? and he could have defended himself. (ok..i'm being picky-picky)

and joe! great comment about being in the victim's shoes!