What does the secondary officer do at a checkpoint?

The role of the secondary officer at a checkpoint is primarily focused on conducting more comprehensive investigations. When a vehicle is flagged for secondary inspection, it typically indicates that the primary officer has identified something that requires further scrutiny. This could involve inspecting the vehicle more thoroughly, questioning the occupants in detail, or checking for contraband or illegal items. The in-depth nature of these investigations is crucial for ensuring safety and enforcement of laws at border checkpoints.

In contrast, the other options involve tasks that may or may not be central to the responsibilities of a secondary officer. While monitoring radio communications is vital for overall operations, it is often handled by other personnel or the primary officer. Similarly, handling paperwork is usually a supporting task rather than the main focus of a secondary officer. Questioning vehicle occupants can indeed be part of the secondary officer's role, but the emphasis on performing in-depth investigations captures the essence of their responsibility more accurately.