Bicycle detail

I arrived to the library around 11:40AM on April 10th. I parked the bike on the racks at 5th & Madison. I tried to lock all parts of the bike frame and wheel; they were too big, so I re-did the lock to only include one part of the bike frame, wheel, and rack. I was moving quickly and may not have locked it properly. I have a heavy-duty multi-hinge ABUS lock that is quite strong. There was a man watching me. He was sitting on the ground, near the library, across from the bike rack. He had a bag and looked like he might be living rough. I went into the library quickly and left again by 11:55AM. When I left, the bike was still there. I walked across the street to the 5th & Madison building. I returned to where I'd parked my bike around 11:55AM. The bike and the lock were gone. The man who had been watching me was also gone.