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San Joaquin County
District Attorney's Office

Bureau of Investigations


David J. Derksen David J. Derksen, Chief Investigator

Contact the Investigation Division: 209-468-3620

The authority of the District Attorney Investigations Division is independent of other local law enforcement agencies. District Attorney Investigators perform a broad range of investigations including investigations into specialized areas not handled by other local law enforcement agencies; investigations reflecting the areas targeted by the San Joaquin County District Attorney to improve the administration of justice; investigations into areas targeted by the state; investigations to assist the operations of other departments/programs; and assistance in trial preparation investigations.

Investigators from the District Attorney's Office are part of the critical incident response team called out when an incident involving the use of lethal force by a peace officer occurs in the county. DA Investigators are also called upon to conduct investigations into suspected misconduct by government officials, public employees, or local agencies.

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