How do fingerprints help solve crimes?

Because each person has a unique set of fingerprints, investigators can determine if a certain person was in a certain place, or touched a certain object, or drove a certain vehicle.

There is always some uncertainty in its use as evidence because a print is seldom a complete and perfect one, and because you usually cannot determine exactly when a print was made. It is extremely difficult but not impossible to fake a print, or to move one from one object to another, or to place an object at a crime scene that already has a person's fingerprint on it.

But it can be powerful circumstantial evidence, such as when prints are found on a gun or other weapon, or in a victim's blood.