About 10 years ago, we had a bad guy sell their car...with our tracker on it. Had to get Highway Patrol to do a traffic stop about 4 hours away while the new owner was headed back home.
Also had a mechanic find a tracker when the bad guy had his car in the shop. This was back when a good tracker was $10,000--not $300 like they are today. So it was a little stressful.