Of course it would be a case by case basis, but maybe a checklist for L.E. used to trigger the test written by the best. Would eliminate any L.E. connected perps imo also as a bonus besides soft heart lead L.E.
I was attempting to make the point that time is critical in missing persons cases - you don't have the luxury of time and stalling an investigation to ask for polygraphs. You don't start there, you may end of there at some point. (IMO).
IMO, polygraphs are just a tool. IMO, during an investigation LE can also tell you that you failed questions on a polygraph, when in fact you didn't, they want to see your reaction. They can tell you that your buddy ratted you out, when they didn't. Truthful people can fail them and liars can sometimes pass them. I digress....