Anti Thief devices.... what works

I agree w/ suspecting tow trucks. When my 1969 Dart was missing in front of my house in 1994, I vaguely recall flashing yellow lights thru the window while I was sleeping. That was in-town Atlanta, so a common occurrence. What cop is going to stop and question a tow truck when they'll just say, "we got a call ..."? Heck, the cops were even complicit in effectively stealing our minivan when my wife was hit. They called the tow truck, she asked them to leave the van at our house 3 blocks away, but the driver refused and took it 4 miles to their impound yard. A detective agreed with me that was auto theft, but wouldn't do anything about it and I was forced to pay mileage and storage.