When can a police officer perform a warrantless arrest related to the mistreatment of police animals?

A warrantless arrest is permissible in certain circumstances, particularly when the police officer has witnessed the commission of a crime directly. In the case of mistreatment of police animals, if an officer observes the act taking place, they have the authority to make an immediate arrest based on their firsthand knowledge of the offense. This principle is rooted in the necessity of allowing law enforcement to act decisively to protect the animals and uphold the law without delay, as waiting for a warrant could exacerbate the situation or lead to further harm.

The other options do not meet the requirement for a warrantless arrest as effectively. Knowing the suspect does not constitute adequate justification for an arrest; reasonable suspicion is a lower standard that does not allow for immediate detention without witnessing a crime; and having a warrant beforehand is contrary to the concept of a warrantless arrest, which means acting without prior judicial approval. Thus, the correct answer focuses on the officer's direct observation of the mistreatment, providing them with the legal authority to act immediately.