I give up on this signature stuff and pubic hairs.

My view is that is probably not related to the crime at all.

His rather wimpy molestation and use of a paintbrush means he probably never undid his pants in order to have a pubic hair be left at the scene. Ofcourse it is possible it was already on an outer garment that he wore.

I think anyone who seems to have enjoyed the murder so much and the sex so little is not going to leave a pubic hair at the scene, indeed he may only be barely capable of it.

Nothing about the pubic hair gives more information than that in his dna from the fingernails and panties.