Yes, that is what I am getting at: the blood evidence - which I find very significant, since this was exactly around the time forensic DNA testing was gaining ground freeing loads of innocent people from incarceration. Spared some the death penalty even.
I know you will write a novel now about how it has no significance, but it will not change that I find it noticable they chose to destroy all blood evidence at that exact time.
According to the above document, Whiddon was given carte blanche to decide what to keep, return and what to destroy. He fel he wasn't familiar enough with the case to make informed decisions so had someone else decide and just followed orders.
There was no reason to need the samples. There were no blood stains that they would need to have DNA tested so no need for the blood samples to use to rule out the victims hence no need for any victim blood. The only DNA tests they ended up doing were worthless as they had no ability to establish a thing. If they had some blood stains from the killer and they feared the stains would prove Sheila was the killer and thus disposed of them that would be one thing. But that is not the case and there objectively was no use for the blood samples.
DNA helps exonerate in cases where the DNA of the killer was left behind or someone other than the defendant was found to have DNA of the victims on them. There was no way to predict any value of any DNA tests given the evidence in this case and the DNA tests ultimate done were indeed pointless.
Interestingly they destroyed Sheila's diaries to keep them from being sold. The Estate it appears would have liked ot try to make money off them that is pretty scummy if the relatives approved of such.