Well I was already speculating, but I can speculate a little more. I guess LE might do that for the same reason they would hide info/fib about any other situation...because they think it may someday help the case somehow. It is hard to even formulate a guess why specifically when we have so little info to go on. Why would they withhold info on how any of the dismembered victims were dismembered, for example? (With or without surgical precision, what kind of tool, etc) Obviously the killer of those victims knows how he dismembered them, but LE has some reason for not divulging that info. The killer always knows how he killed someone, but LE withholds info all the time.
But again, it could all be coincidence, and Truthspider's fox got the hyoid bone. Or the cover-up angle, for whatever reason. It just seems to me there are far too many coincidences we are being asked to believe about SG. If she really freaked out for no reason, imagined the threat, and threw herself in a puddle around the way from all the other bodies, then that was one mighty cocktail she had that set it all off....perhaps a cocktail of Murphy's Law Scotch and Bad Luck Benzos.