The role of the Deputy Incident Commander?

The primary reason to have a Deputy IC is to perform IC functions as relief for the IC, perhaps as preparation for becoming IC in the next operational period.

The Deputy IC will also carry out specific IC tasks as requested by the IC and may represent an assisting agency with shared jurisdiction or about to receive jurisdiction from the IC, as the incident changes mode.

For example, a fire IC may select a deputy from the Fire Marshal's Office (or other investigators) when the fire appears to be of suspicious origins. The Deputy IC may be instructed to oversee IC functions (during fire suppression) related to preserving evidence or providing access for investigators while firefighters are working for their own objectives. Once the fire is out and the fire operations terminated, the Deputy IC may easily transition to become the IC for the remainder of the investigation portion of the incident, with law enforcement operations.