There are some TV channels that show drammtizations of actual criminal
investigations. I watched one such story the other day. The detectives
had surveillance recordings, and they were looking when a break in a
fence occurred. The started some time after the incident and they went
backwards day by day by day. It took them 14 iterations. When they found
the D day they watched the tape for 24 hrs until the incident occurred.
Things that are self-evident to most of us apparently never occurred to
the investigators. Lot of taxpayers money could have been saved.