Major Crimes District

DPS OfficersOverview / History

The Major Crimes District provides two investigative functions which are performed by the Special Investigations Unit (SIU), the General Investigations Unit (GIU) and the Vehicular Crimes Unit (VCU). The Special Investigations Unit investigates all critical incidents in the Department which may involve death or serious injury. SIU and GIU also provide investigative support to other units during the investigation of less serious critical incidents. SIU and GIU will investigate alleged criminal misconduct by departmental employees and alleged public official and employee misconduct for political subdivisions throughout Arizona. In addition, SIU and GIU will investigate critical incidents and allegations of criminal misconduct involving employees of city, county, state, tribal and federal agencies. Furthermore, SIU and GIU will assist city, county, state, tribal and federal law enforcement agencies by providing investigative support into serious crimes occurring within their communities as well as providing support to the Highway Patrol Division to include investigations involving aggravated assault, homicide, hit-and-run collisions, and narcotic interdiction. 

The Vehicular Crimes Unit (VCU) was formed in 1976 (known then as the Accident Reconstruction Unit) as a result of the Arizona Department of Public Safety recognizing the need for specially trained officers in the area of collision reconstruction. This early unit provided accident investigation and reconstruction expertise to the Department and other criminal justice agencies throughout Arizona. On April 1, 2000, the Reconstruction Unit from the crime laboratory and the Metro Vehicular Crimes Unit merged to form the current Vehicular Crimes Unit.

The Vehicular Crimes Unit's primary mission is to provide investigative expertise and expert court testimony when a vehicle is the instrumentality in a homicide (first degree murder, manslaughter or negligent homicide), aggravated assault and related crimes; and/or when the state of Arizona may be exposed to civil litigation as a result of a collision. The units’ secondary mission is to provide classroom instruction in the area of collision investigation and reconstruction to DPS officers as well as officers from other agencies throughout the state.

Today the purpose of collision investigation can be broken into three areas:

  • To provide drivers, vehicle owners and others involved in a collision with the factual information necessary for processing claims and/or possible civil litigation.
  • To collect factual statistical data for the design and use in collision prevention programs and safety programs for safer roads, safer vehicles, seat belts, airbags, brakes, tires, etc., better laws.
  • To determine statutory violations, if any, and to document those facts which prove the elements of those violations.

There are many specialized computer software programs and items of equipment essential to the modern collision investigator and reconstructionist. The current police reconstructionists will find themselves presenting their opinions alongside private sector reconstructionists hired by the defendant or plaintiff. Many times the private sector reconstructionists are retired officers with years of experience, engineers with extensive educational backgrounds, and both with access to the latest in reconstruction gadgetry. The Department of Public Safety, Vehicular Crimes Unit, with the assistance of the Governor's Office of Highway Safety, remains a leader in the use of modern technology.

The equipment and software is used to measure and diagram Collision scenes; collect specific physical data such as grade, super elevations and/or drag factor; run complex mathematical formulas and the computer simulations based on physical scene evidence and scientific principals. The following list gives an overview of a few of the items being used by the Department of Public Safety:

  • Trimble Global Positioning System:
    Used to measure and record a computerized mapping file of the collision scenes which is downloadable into any one of many mapping software programs. This system can be operated by one investigator and relies on a line sight or clear air to at least 5 satellites orbiting overhead.
  • Vericom 2000 and G-Analyst:
    This equipment tests the road surfaces and determines the friction value at the location of the test. They can measure deceleration forces, acceleration forces and lateral forces.
  • Photo modeler Pro:
    This software, under specific conditions, allows measurements to be taken from existing photographs of a collision or crime scene.
  • AutoCAD Lt., Crime Zone, Visio Technical, Generic CADD, and a few other computer programs:
    All of these programs are used by the members of the Vehicular Crimes Unit to download and complete the scale collision diagrams. AutoCAD is our primary drafting program due to its compatibility and the training available through our local community colleges.
  • HVE2D:
    This is a state of the art, 2 dimensional collision simulation program allowing us to test and confirm our collision theories based on calculations made from the evidence at the scene.