Factual error: Abby says she ran X-ray chromatography. There is no such thing. I assume she meant X-ray crystallography.
Factual error: Obviously written to make the story interesting, but Gibbs says that the first criminal caught by DNA was a Mafia don in Sicily. Well as anyone interested in forensics knows it was Colin Pitchfork in England.
Chosen answer: "Policing your brass", means to pick up your expended shell casings, after firing your rifle, or pistol.
pross79