As a LE officer, and a Cyber Cop too boot, 80-90% of the info we gather is from public sources. Mind you, A photo of a license plate is much harder to search for than text based info. Unlike the shows on TV, there is no magic software nor hardware that can scan a blurry, pixilated photo and instantly tell what color of underwear the suspect was wearing last Tuesday while he was visiting China.
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I saw NCIS ...they were looking at a out door security video of a car 10 yards away with two guys talking and one had a piece of paper in his hand ..so they froze the picture zoomed onto the first guy..then and zoomed in on the piece of paper ..hit a few keys on the magic computer and was able to read the barcode on it and with less then a min.. they did a scan of the barcode and found it to be a plane ticket reciept.....lol
I love tv shows.