Here’s where it gets sneaky. Even if the hair shaft is dead, it still has mitochondrial DNA (mtDNA) inside it.
Think of mtDNA as a weaker, but still useful, cousin to nuclear DNA. It’s passed down from mother to child, so it can’t tell you apart from your sibling.
How Does a Hair DNA Test Work? - DNA Diagnostics Center (DDC)
But it can tie a hair to a family line. It’s like a vague, maternal fingerprint—not unique, but helpful for narrowing things down.
How Labs Actually Do It
Real forensic labs don’t just wave a magic wand. They need a good sample. If the hair has the root, they can run STR analysis—that’s the fancy test for nuclear DNA.
If there’s no root? They use the mtDNA from the shaft. But here’s the kicker: it takes a lot of hair. We’re talking about several strands, not one.
And the process is slow. Days, not minutes. So that TV detective is definitely rushing things.
