Final answer:
The first officer's principle concern at this time would be preserving evidence.
Step-by-step explanation:
The first officer's principle concern at this time would be preserving evidence. When investigating a crime scene, it is crucial to ensure that any potential evidence is not disturbed or destroyed. This includes not contaminating the crime scene, protecting any physical evidence present, and documenting the scene through photographs or sketches. Preserving evidence is essential for a thorough investigation and potential prosecution of the case.