What should an officer do first upon arriving at a crime scene?

An officer's first priority upon arriving at a crime scene is to ensure the safety of the scene and secure it from contamination. This is paramount because preserving the integrity of the evidence is vital for the investigation and any potential prosecution. Securing the scene helps to protect physical evidence from being altered or destroyed, which could hinder the investigation and compromise the case.

Ensuring safety also involves evaluating any risks associated with the scene, including the presence of potential threats to the officer or others, such as firearms or aggressive individuals. Once the scene is secured and made safe, the officer can then proceed to other important steps such as collecting evidence and interviewing witnesses, but these actions come after the initial security and safety measures are in place.