Bicycle detail

As I left my apartment for work this morning (~6:30 am), I noticed that both of my mountain bikes were missing from my 2nd story balcony. They were definitely there the previous evening when I went on my balcony to spray a wasp nest. Both bikes were stored under a tarp, and the balcony is only accessible through my living room. They might have used a ladder, or possibly jumped from the staircase to the balcony. Either way, the theft must've been planned in advance and involved at least two people. A stranger did knock on my door the day before, asking for someone named Bill (I don't know anyone named Bill). He was a nondescript mid-20's white male with dark hair, and he and his presumed girlfriend walked out of the apartment courtyard after I closed the door. Other than that, I have no leads.