That person is called a forensic investigator or a crime scene investigator. They are responsible for collecting, analyzing, and preserving physical evidence from crime scenes in order to help solve crimes and provide evidence for legal proceedings.
They are not responsible for the crime of a 20 year old person no matter where the person lives, unless they somehow helped commit the crime in some way.
Possibly because I am a portrait or a picture. Framing a picture isn't a crime.
Police are responsible for controlling crime.
It's called an accomplice, or a co-conspirator.
Yes. A crime happened. If the other person tried to kill you, then the other person is responsible for the crime even though you did the killing. If it was simply a fight and you suddenly decided to kill the other guy, then you committed a crime.
A crime investigation job requires an individual to use science and psychology to determine the cause of a crime. This helps to track down the person or people responsible.
Possibly. You will have to check with your local law enforcement agency to determine the answer to the question. Although "a crime is a crime," the immediate question that is going to be asked is, "Why the delay?"
They are called the Coroner.
Criminal, perpetrator, suspect, person of interest.
To the best of my knowledge the professional person who investigates a crime where it was perpetrated is called "a crime on scene investigator".
An accomplice is a co-conspirator or actor in the commission of a crime. A person who assists in the plan but does not carry out the crime is called a conspirator. A person who assists in the plan and carries out the crime along is an accomplice.