An individual who leaves any trace of DNA can be analyzing and can give the height, eye color, hair color, age, sex, and facial features.. That's a great help in crime solving.
Nah.
A good guess (but probably no very accurate) can be made, but will be of little use in solving a crime.
Eye and hair colour can easily be be change from what is natural.
DNA is very useful in matching a suspect to a crime one e they have already nabbed the suspect, not before.