DNA fingerprinting has been used in criminal investigations because

DNA fingerprinting | Definition, Examples, & Facts | Britannica

a
criminals leave DNA samples behind them when they touch an object at a crime scene.
b
DNA analysis allows investigators to distinguish body cells of different individuals, who are unlikely to have the same DNA.
c
bacterial DNA on the hands of criminals may provide a clue as to where that person was when the crime was committed.
d
DNA found on murder weapons is easy to identify.

b

DNA analysis allows investigators to distinguish body cells of different individuals, who are unlikely to have the same DNA.