The age of an UNKNOWN donor cannot be determined. Only in cases where the DNA comes from fluids that are associated with puberty (semen, menstrual fluid, etc) can the donor be assumed to be over the age of puberty, but even then, the specific age cannot be determined. In cases where the DNA has come from a body or body parts (teeth, bone, etc) the age can be generalized as to whether the remains come from an adult male or female.
The age of a known donor can be determined because the donor is, well, KNOWN, not because of specific markers in the DNA itself but simply because you know who it was.
I agree with Holdon- the donor would have had to have touched other things between a previous victim and JB. Unless the previous victim was right next to JB and the abuse occurred immediately before, and we know that wasn't the case. Even assuming latex gloves were worn driving or walking to the house, other surfaces would have to be touched between victims. We can also assume that the donor's fingers were not covered by a glove, or there would be no "touch DNA". If the skin cells came from a previous victim and were on the surfaces of a glove, as was suggested, then the donor is another victim and DEFINITELY not the killer and Lacy has caused this case irreparable harm. (she's done that anyway).
That is why it was so important NOT to clear anyone in this case and NOT to say the donor WAS the killer.
We know from the injuries that something penetrated her vagina at some point. The coroner said in his opinion it was a finger. But as I have said, it is only conjecture that the sexual activity had anything to do with her death. It may have, or or it may have been something that occurred unrelated to her death. This is particularly likely if PDI. Someone was abusing JB, and more than once. Not all her vaginal trauma was from the time of death. If PR knew of it and helped with the cover-up to protect that person, that still doesn't mean that the abuse led to her being killed, only that Patsy needed to prevent the abuse and the abuser from being discovered.
If it was JDI, JARDI then the abuse that occurred that night WAS likely what led to her death, because if she screamed during it and was bashed to silence her, and would explain the acute injuries (from that night) AND the previous injuries ("this was a game that was played before"). It also explains the blood that was wiped from her thighs and pubic area.
I am RDI, or at least R KNOWS WHO DI.
I can't rule out any R as being the one who inserted the broken paintbrush. But I can also imagine the bleeding being caused by douching, the scream resulting from that, and whatever bashed her skull happening then.
What is so frustrating in this case is there are three distinct RDI possibilities and each one requires the cooperation of the parents in covering it up.
