The private citizen generally may arrest without a warrant:

A private citizen has the authority to make an arrest without a warrant primarily in situations where a crime is committed in their presence. This principle is rooted in the concept of citizen’s arrest, which allows individuals to act to maintain public order and safety when they witness a crime taking place.

When a private person observes a crime occurring, they are often justified in taking immediate action to prevent further harm, protect other individuals, or apprehend the suspect. This act must be based on actual observation rather than speculation or hearsay. The requirement for the crime to occur in their presence ensures that the citizen is fully aware of what transpired, providing a clear basis for their actions.

In contrast, situations involving felonies, misdemeanors, or "reasonable cause" considerations might complicate the legal standing for a citizen's arrest. While it may seem logical that one could arrest for a felony or exert a belief of reasonable cause, legal guidelines generally emphasize the necessity of witnessing the crime to justify an immediate arrest without a warrant.