There have been many security devices used over the last few centuries and millennia to keep the peace and ensure that residents of a certain town were kept safe and some of the most interesting things that early security forces would do in China over three thousand years ago was the rice test which was designed as a fairly accurate lie detector test.  Although this technique would be unheard of in today's police environments or Elk Grove private security firms, three thousand years ago it was the best way to figure out if someone was lying.