Most trace evidence is harder to analyze. It must be sent to crime laboratories, where high-tech equipment can identify it.For example, a laboratory may analyze broken window glass from a crime scene.How does it bend light that shines into it?What chemicals is it made of?With a report from the lad, a CSI can search a computer database for car models that have the right kind of glass.Only a few models will match.
The police may not have found the exact crime car, but they will know what kinds to look for.