Shoes got stolen in 24 Hour Fitness

Just need to rant. I switched outside shoes to gym shoes and left them outside of the locker (because I don’t want to get dirt into the locker). After I finished my workout, I couldn’t find my shoes. I thought someone was doing a prank and looked into every locker, but still no luck. Just never thought people would steal used shoes in the gym, especially they are not new and a little dirty.