Bicycle detail

Bike was parked on sidewalk of NE 60th Ave at entrance to Max station, locked to a sign pole with a chain. The chain was found cut on the ground, along with helmet, when we returned, but the bike was missing. It was parked there between 6pm and 8:30pm so happened then. Another bike was parked next to it on the same pole with a U-lock but was not stolen. I still have the cut chain. We bought the bike used from a local bike rental company when they sold their fleet in May, and it still has a couple of identifiying stickers on the frame. I have a picture of the serial number which is G71385-2 (There is also a longer number which I think is the model above it WBD2541 01600 on the bottom bracket as well)