Authorities screwed up by not doing autopsy right away. Like sheriff pointed out, they didn't need permission from family, coroner could have ordered it.
Coroner in Idaho is an elected position, and this particular coroner only has High School diploma, not even B.S., let alone M.D. Not sure how she is supposed to be figuring out if death is suspicious enough to order an autopsy, but Tammy was a fairly young woman with no history of health problems. If autopsy was done right away, and blood was collected right away, it would have been easier to figure out what killed Tammy. Now it might be impossible.