Hair and fibers and other trace evidence are often unknowingly left at the crime scene by the perpetrator. And those clever CSI folks can find these tidbits and analyze them. From hair, they can usually determine the species (human, cat, dog?), the color, the thickness and curliness, whether it was cut or yanked out, and other things.
But what if the hair has been altered with coloring or various chemical treatments? No problem. In fact, such alterations could add another layer of individuality to hair found at a crime scene. Using Surface-enhanced Raman Spectroscopy (SERS), dyes and chemical treatments can be analyzed and such analysis can lead to the type of treatment and even the manufacturer of the product. This could prove to be critical evidence in connecting a suspect to a crime scene.
The Crime Fiction Writer's Blog 
Bud Crawford
May 6, 2015 at 10:15 am
Given the recent FBI admissions of forced and slanted results, it will take a while to repair credibility for this aspect of forensics.
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D.P. Lyle, MD
May 6, 2015 at 10:25 am
Yes it will but this is more forensic chemistry than it is hair and fiber analysis so would be a bit more precise—at least it should be. We’ll see.
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Bud Crawford
May 7, 2015 at 2:35 pm
Yeah, high-tech analysis should be more precise. And maybe the data could be shared with defense technicians for rebuttal. That was one problem with the hair, old style. The agents were probably (in their minds) “helping convict criminals.” But since they were the only experts, very hard to challenge, their prosecution-leaning testimony seems to have tipped the scales the wrong way in a significant number of cases.
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Cheryl B. Dale
May 6, 2015 at 1:47 pm
Sounds like it’ll be easier to connect the criminal to the crime!
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