A criminal.
Yes, a person can be prosecuted for a crime committed in another country if the crime is considered illegal in both the country where it was committed and the country where the person is being prosecuted. This is known as extraterritorial jurisdiction.
Yes a person can be charged with a crime
Extradition, or extraditing depends on if the person has been taken to the other state or not.
an accessory after the fact may be what you are looking for
The perpetrator of a crime is the person who actually committed the crime. A suspect may or may not have committed the crime. A suspect has not been confirmed as being the perpetrator.
a witness
Suspect.
The crime committed when someone threatens another person with a gun is typically considered assault with a deadly weapon.
If the person was still married to the first wife when the second marriage was performed then this is a crime (not a crime committed by the Judge unless the judge KNEW the person was already married - but a crime committed by the person who is still married). The second marriage is not legal (no matter who performed it) and the person who was still married has committed the crime of polygamy.
Criminal, perpetrator, suspect, person of interest.
the three elements of a crime should be present ( motive, knowledge, and opportunity ) for the conviction of a person committed a crime.
Treason.