There is documentary evidence supporting DNA tests,written by J.Hayward in 1985,which showed that blood inside a moderator belonged to RWB,or a mixture of June and Neville ( Totally unrelated to Sheila )
Though interestingly,RWB shared the same blood grouping as Sheila but at no time did it mention that the blood was Sheilas'.
Members of the jury weren't informed of this,so they naturally assumed that the blood belonged to Sheila.
Also,DNA found on a rifle of an un-named male could have been that of Neville,AP or RWB.DNA not necessarily meaning blood.