What should be the first step when arriving at a crime scene?

When arriving at a crime scene, the foremost priority is to secure the scene and ensure safety. This step is critical for several reasons. First, it protects the integrity of the scene by preventing contamination or alteration of evidence. Securing the scene allows law enforcement and investigators to control access, ensuring that only authorized personnel enter and exit, which maintains the evidence's chain of custody.

Additionally, ensuring the safety of all individuals present is paramount. There could be potential hazards, such as ongoing criminal activity, dangerous conditions, or even biological hazards that could pose risks to first responders or civilians. By establishing a secure perimeter, any immediate threats can be addressed before beginning the investigative process.

This initial step sets the foundation for a thorough and effective investigation, allowing for the subsequent actions, such as evidence collection, witness interviews, and documentation, to be conducted in a safe and controlled environment.