To charge someone with a crime, the government only needs probable cause to believe that the person committed the crime. It is, therefore, possible that a person could be charged with a crime though they could be later found not guilty. All the government needs is enough evidence to support probable cause (remember that evidence includes testimony - what people say; it is not just physical objects or documents [videos, tapes, etc.]). If the government can establish probably cause, which is simply that it is more likely that a person was involved in the crime than not, then the person can face criminal charges. This is different than the standard of a trial - beyond a reasonable doubt.
Answered on Feb 20th, 2013 at 11:57 PM