[jocoyn]

Can't find a body because of dog odors
No that is absolutely silly. The dogs can pick out the human decomp odor.

One of my most fun problems a friend set up was to hide a small training aid in a chicken house with chickens and turkeys and ducks all flapping about [it was an open barn in fenced area....but hundreds of birds and an odor to match]...no problem at all.

That was a small training aid, not a whole human body. We have done all kinds of crazy things to mask the odor. Burn it, cover it with lime, put a small sample near animal decomp [that sample can get cross contaminated with animal odors though so not something you would reuse down the line], place in odiferous places with gasoline odors, spice odors, mulch piles, etc.

Less than 12 hours?
Sure. Grim pinpointed a body in a lake that had been down for all of 3 hours. 75 feet down. The flies that lay eggs on bodies can actually discern when death is imminent and can start gathering around openings like nose and mouth even before death.

You figure they want FEMA dogs to ignore the recently deceased in a disaster. They would not be much use if they were finding fresh bodies and I have heard anecdotal that they too can differentiate stressed from alive from dead but I have nothing to quantify that one.