TL;DR There are many professional and thoughtful police officers and deputies that take every precaution to protect citizens' privacy. Because of their hard work and professionalism, logs of the last 24 hours were more than enough to help their investigation.
While working for a sizable WISP in 2010, we were approached by a local police office asking if we could help them pin point the location of a murder suspect on the run from Wisconsin.
The suspect had used our wireless mesh network to access his MySpace account, which was being monitored. Because our logins reset every 24 hours and because of the NAT'd nature of our wireless network, we were able to give the police approximately 10 locations where the suspect might have been within a 200' radius. The police followed up on those locations and were able to find where suspect had been staying.
Unfortunately, they missed him by a few hours and he was eventually caught in Colorado a few days later. It was an eye opening experience. The officers reiterated again and again that they wanted as little extraneous information as possible and did not want to involve anyone that had no connection.