But if so, why would killer spend so much obvious time and energy jimmying off that side door handle? And then wander halls for 30 minutes? The exercise group was normally held outside. How much easier (if using a gun) to drive by and quickly shoot them from a getaway car with muddied plates. And, if the class (as read online) moved indoors, killer could simply adjust plans to drive by, pop inside (door presumably opened at 5 for class), gun them down, jump back into his car and speed away.
I don't know...this still (to me) smacks of someone going 30 minutes early to specifically lay in wait for an individual.