Which of the following is a requirement for probable cause to arrest?

Probable cause to arrest is fundamentally based on the principle that there must be a reasonable belief that a crime has been committed or is in the process of being committed. This means that law enforcement officers must have more than just a vague suspicion; they need concrete evidence or circumstances that would lead a reasonable person to believe that an individual has engaged in unlawful behavior.

In this context, the existence of a crime—be it completed or ongoing—serves as the backbone of establishing probable cause. If no crime has taken place or is happening, then there is no legal basis for an arrest, regardless of other surrounding factors.

The other options do not constitute requirements for probable cause. For example, while the suspect's presence in public may give law enforcement the opportunity to observe behavior, it does not inherently indicate that a crime has occurred. Similarly, while witness testimony can strengthen a case, it is not a necessary condition for probable cause if other corroborating evidence is present. Lastly, a suspect's criminal record might provide context but does not automatically justify an arrest unless there is also evidence of current unlawful activity. Thus, the requirement that a crime has been or is being committed is essential for establishing probable cause to arrest.