Bicycle detail

My apartment building has recessed back porches inside two tall (>7") gates which must be locked with a key every time you enter/leave. Both gates were locked as of 9:45 this morning, but dog owners may have locked them since last night. I have been leaving my bike on my first-floor back porch when not in use, out of sight from the street and the alley. I took my dog out around 11 last night and passed it as we came back inside. This morning, around 8 AM, it was gone. It had not been moved by a neighbor and was not found elsewhere on the property. The bike included panniers, a U-lock and cord, multiple sets of LED lights (front and back), a back rack to attach the panniers, a Roscoe Village Bikes sticker and a reflective Chicago Bikes sticker with six-pointed stars/a cartoon of the skyline on the body. An air pump alongside it was not stolen. The bike was purchased for >$500 in 2013 and additional accessories probably bump up the lost property value over $750.