This website has some informative information:
http://criminal.lawyers.com/criminal-law-basics/criminal-law-crime-definition-faqs.html
Q: Can an event be both a criminal and civil offense?
A: Yes. Depending on the circumstances, a single event may be tried in both courts. For example, a defendant may be tried in criminal court for murder, and later that same defendant may be sued in civil court by the victim's family for wrongful death.
Q: Can being present at the scene of a crime make you guilty?
A: In most states, juries are instructed that merely being present at the scene of a crime, even with guilty knowledge that a crime is being committed, isn't enough to convict a person of a crime.
But there are principles of criminal liability that apply to people other than the person who actually committed*a crime. For example, under federal law there is a crime called "misprision" of a felony, which applies to a person who has actual knowledge of the commission of a felony and doesn't report it to the authorities.
Also, under federal and most state*laws, a person can be held criminally liable as an "accessory after the fact" if she has knowledge that a crime was committed and assists the offender to hinder his apprehension, trial or punishment. You can also be guilty of aiding and abetting*a crime if you help another person in committing the crime, with knowledge of the criminal nature of the act they're committing.
Additionally, a person who agrees with another person to commit a crime, after which the other person commits a criminal act to further their agreement, may be guilty of conspiracy.
But merely witnessing a crime, without any participation in it and without providing assistance, isn't a crime.
Q: What constitutes "aiding and abetting?"
A: Aiding and abetting is a theory of criminal liability under federal and most state laws. You can be guilty of a crime either as a principal perpetrator - the "main" actor - or as an aider and abettor.
Aiding and abetting applies to someone who assists or helps one or more other people commit a crime.*To be held accountable as an aider and abettor, you must know of the criminal objective and do something to make it succeed. For example, if you drive your friend to a meeting where you know your friend is going to buy drugs, you may be an aider and abettor in the drug transaction.
The key here is knowledge. While the level of participation of the aider and abettor may be relatively minor, the prosecution must show more than presence in a vehicle carrying drugs or association with conspirators known to be involved in a crime.
In other words, mere presence at the scene of a crime, even with guilty knowledge that a crime is being committed, isn't enough to make you liable for the crime itself, unless and until you do something to help the crime succeed.
Under federal law, the punishment for someone who aids and abets a crime is the same as the punishment for the person who principally committed the crime. In some states, the punishment may be less.
Q: What exactly is the felony murder law?
A: Felony murder means that all persons engaged in a felony are liable for murder if one of them kills a person during the crime.
For example, if A and B rob a bank and as they're escaping B shoots and kills a bank employee, even by accident, both A and B may be charged with murder unfer the felony murder rule.
