Looking at #1724 again I would have thought had she grabbed her mother by the neck the nails might have been chipped. Were June's fingernails scrutinized for residue of any kind? It's unlikely Jeremy was involved in these marks had he worn gloves throughout.
Nails won't chip if they're sunk into flesh,unless you mean that had her nails been chipped prior to the neck-grab,they might have left signs ?
Unfortunately nobody's fingernails had scrapings taken from beneath them.

Maybe the said marks/prints weren't big enough in size to indicate that they were done by a male,or we'd have heard long before now.