Are the discovery and/or autopsy reports available online?
I don't know that there's anything official but the documentary depicts strands of Kathleen's hair found in her own hands, and microscopic evidence of feathers, needles, and wood splinters as cited by others.
In other words, hair tested to be the victim's hair in her hands is notable whether or not it be a clump or strands. MOO
ETA: add link w/autopsy which confirms hair in each hand, pine needles, and splinters in scalp hair. I'm not seeing 3-feathers but perhaps others better and cyphering the handwriting.