what's in it for reichenbach to lie? i don't know exactly what he wrote down that day, but police officers keep notes of all their activities. at the time, the case had not yet gained the momentum in the national media that the case now has. wasn't reichenbach just doing his job and reporting what he saw?
also, whenever it is below 32, every single drop of water is not necessarily frozen. the sun can melt ice even if the temperature is below 32. or the pathways could be clear but the grass has frost, as you pointed out. there are a number of different scenarios. i don't think the temperature is entirely dispositive on this issue.
think about it the other way around...when a puddle evaporates, does that mean that it is 212 degrees out? ok, now i just confused myself. how does water evaporate, because it's never 212 degrees out! if you stuck your hand in a puddle that was slowly evaporating, do you burn yourself as though you stuck your hand in a pot of boiling water? look out google! here i come...