how do forensic identify the hit-and-run car with a paint chip?

Question

using spectroscopy

Answer 1

Let's assume for a second that the car was blue. Blue paint isn't just blue paint. The blue paint used by Mercedes Benz and by Chevrolet are different. The blue paint that Chevrolet used in 1996 is different than the blue paint used on a 2008 Impala. They can narrow it down to manufacturer and approximate year pretty easily.

Answer 2

paint along with many other things has it's own specific signature in the spectrum , even things that are seemingly the same will show up differently much like a fingerprint .