A family members home was broken into, we checked the routers DHCP logs to determine what phones connected that day.

We were able to determine the person AND the time it happened since an IP is only held on for 24 hours before being released. The person ended up being a friend that had connected to the WiFi in the past! (Yes, that friendship is very over.)

It was a real life CSI moment, and yes, criminals are generally oblivious to their phone identifying them! Good thing for my family member!