I'm also very suspicious that no photograph exists of the 1/4 inch long blood flake, plus the tests in 1999 couldn't find any trace of Shelia and also found the DNA of an unknown male how did that get in there?
I don't know whether such a photograph exists or not, either way I don't find that particularly suspicious.
The tests in 1999 found DNA which closely matched a blood relative of Sheila, but it is not sufficient in law to prove that it 'was' from Sheila. I think it's extremely likely however, that it was.
I always assumed the unidentified male DNA was one of the twins, but it's also possible that the highly sensitive LC tests picked up DNA that was from contamination over the years.
In the end, they couldn't even be sure the DNA was derived from blood, the results were largely meaningless.