The process for analyzing DNA is complicated. But, here are the very basic steps in an analysis in determining whether there is a match between a suspect and a sample from the crime scene. A police identification unit first collects samples of blood, saliva, semen, skin or hair from the crime scene. The genetic material is separated from the rest of the cells collected in a sample.
Scientists first determine how much DNA there is for analysis.
The DNA is tagged so that it will fluoresce later in the process. The DNA fragments are then placed in a gel and an electrical current is applied. This is called electrophoresis . Lasers light up the fluorescent tags. The fragments are measured and analyzed by a computer.