What should be done first before collecting physical evidence at a crime scene?

Securing and controlling the crime scene is of paramount importance before any evidence collection can take place. This initial step ensures that the scene is preserved, protecting it from contamination, alteration, or loss of evidence due to unauthorized access or disturbances. By establishing a perimeter and controlling access to the area, investigators can maintain the integrity of the crime scene, which is crucial for the validity of the forensic evidence to be gathered later.

Once the scene is secured, other actions such as documenting evidence can follow, but the priority must always be to ensure the safety of the investigators and the preservation of the scene itself. This also sets the stage for thorough and unbiased evidence collection and ensures that the entire investigation process builds on a solid foundation.