Forensic scientists are specialists in identifying hair characteristics. Differences in hair color, structure, and scale patterns are readily visible under a transmitted light microscope. Although hair is not a unique identifier, a comparative analysis of several samples can eliminate mismatches. Several forensic scientists will be asked to independently compare hair samples as part of the Chicago Historical Society's collaborative research project.
Hair attributed to the site of Lincoln's bullet wound, 20X magnification.
Mitochondrial DNA is passed on from mother to child. Although mutations sometimes occur, mitochondrial DNA can usually be traced through maternal relatives. Investigators are searching for female relatives of Lincoln's mother, Nancy Hanks Lincoln; the last link in the chain could be a living male relative. Nancy Lincoln's genealogy has been a matter of dispute. Lincoln's law partner, William Herndon, suggested that she was illegitimate. Investigators would also have to find a relative willing to donate blood!
A microscopic examination of debris caught between the teeth of the comb reveals hair roots and large pieces of dandruff. Each flake of dandruff can contain ten to thirty human cells, each with their own supply of mitochondrial DNA. If the comb is authentic and the dandruff is Lincoln's, these cells could provide a large and readily obtainable source of Lincoln DNA.
