"Test shots on live pigs destined for slaughter showed that bone particles are a feature of backspatter from close-range shots to heads. Contamination of nearby surfaces by bone fragments and bone-plus-bullet fragments, as well as other organic debris, appears to be quite heavy."
"Detection of Bone and Bone-Plus-Bullet Particles in Backspatter from Close-Range Shots to Heads," Journal of Forensic Sciences, Vol. 36, No. 6, 1991, pp. 1745-1752,
Adam were is all the biological material from Nicholas 3 contact head shots?