On 'Mornings With Ken and Bernie' today former interim Chief of Lafayette Police Ralph Peters explained the how's and why's of "officer involved" shootings.  Peters said,

Typically most agencies call an impartial outside agency into investigate and at the same time the department conducts it's own internal investigation to see if it's officer violated any of it's policies or procedures.

When asked what would happen if an officer were cleared by State Police but found to be in violation of department policies and procedures Peters responded,

The final authority for the department would have to decide what discipline to take against the officer.  In some instances an officer could be suspended with pay, without pay or fired.

Listen to the entire interview: