How much evidence is needed to show probable cause?

Probable cause requires a reasonable belief that a crime has been committed or that evidence of a crime is present in a specific location. The evidence does not need to meet the level of proof beyond a reasonable doubt, but it must be more than mere suspicion or speculation. Typically, law enforcement officers must present facts or circumstances that would lead a reasonable person to conclude that a crime is likely occurring or has occurred. The determination of probable cause is often made by a judge or magistrate based on the totality of the circumstances.