a witness
an accessory after the fact may be what you are looking for
If they were not in a competition, they should call the police. They have committed the crime of battery, which is illegal.
Dora or Jane or whatever you want to call her she is the person who stands by the door and is Emily's guardian.
A person who commits a crime is known as a criminal.
There is no specific word for this.
They are called the Coroner.
Criminal sociopath.
Such a person would be an accomplice or a partner in crime.
say kaleb is cool
They call it deadly force, but if you resist with a deadly weapon and you have committed a serious crime and they find you, they can.
greedy, unethical, with out shame or morals
It depends on whether they think the person is part of the crime as well. If they do, then the person is called an accomplice... someone who helped the suspect commit the crime. If not, then the person is just an associate... someone who knows the suspect and might be able to identify where he or she is.