. DNA replication is a highly accurate process, but mistakes can occasionally occur as when a DNA polymerase inserts a wrong base. Uncorrected mistakes may sometimes lead to serious consequences, such as cancer. ... Mutations: In this interactive, you can “edit” a DNA strand and cause a mutation.
Some mutations have a positive effect on the organism in which they occur. They are called beneficial mutations. ... They increase an organism's changes of surviving or reproducing, so they are likely to become more common over time. There are several well-known examples of beneficial mutations.
DNA/fingerprints are all unique, therefor it is easy to match a fingerprint to a person thus they use this mechanism in criminal investigations because only one person woul have matching DNA to the prints on the scene, and that is the criminal.
Hope this helps :)