Multiple Agency Forensic Mapping Technique

At Expansive Critical Incident Scene

In these times, it is not unusual for several agencies to be called upon to document a very large potential crime scene, following a natural, manmade, or criminal-intent related calamity.   

As demonstrated in the below view where 4 agencies were called for assistance, and two agencies provided more than one Instrument, with certain communications in place, this can be a very successful and easy to manage process, with the goal of downloading all raw data into one common diagramming software.  

For this example, VistaFX is chosen for it’s ease of use, popularity, precision of evidence point location and simplistic approach to this otherwise, seemingly intimidating and technical undertaking. 

As agencies are recruited to bring their Forensic Mapping instruments and equipment to the scene, coordination of where the ideal RP (reference point) location for each agency to be location should only depend on securing the most evidence gathering ability, and not whether agencies will be able to see the other agencies RP. 

Instead, this will be determined by positioning specific “MP” points (merge points) from where ‘side-by-side’ agencies are within sight.

Each agency then would be responsible for the specific Coding and documenting of the two (2) “MP” (merge point) locations, on either side of them.

v  RECOMMENDED SCENE CHECKLIST: 

Generally, forensic evidence recovery teams will first Flag or otherwise Mark relevant evidence .. or .. this may be a fluid operation such that this would be an on-going process and they would work in conjunction with the Forensic Mapping teams.

1-    Determine the magnitude of the scene.  How big or expansive of an area is of concern?

2-    Important:  Determine QUICKLY (!) who will be the lead agency and/or what person or group of investigators will lead other responding agencies using Forensic Mapping (total station) techniques for electronic scene documentation.

3-    “Lead agency Coordinator” should decide whether 2D or 3D features of Scene are appropriate.

4-    Determine a common public safety radio channel for all communications, if possible.

5-    Coordinate Forensic Mapping process with chief of evidence marking detail.

6-    Determine the number of volunteering agencies, offering their Forensic Mapping expertise. 

7-    Assure reasonable reliability of Instruments, back-up batteries, data collectors (consider available memory and erase all old Scenes!), batteries, tripods, prisms, and prism-poles.  The more prism-poles available, the better!

8-    Position support vehicles nearby for necessary battery charging and other unit support.

9-    Locate, in concert with on-site forensic evidence recovery teams, where each Forensic Mapping unit (total station) can best be positioned to document without overlapping, as much relevant evidence as possible.

10- If lead agency wishes to use a GRID technique for marking, documenting and collecting of evidence, and if using Vista mFX data collection software, active GRID function.  The same viewed GRID section seen on the data collector, will be the same GRID viewed in VistaFX drawing software.  Caution- The EvR version software has GRID feature only on data collector portion of their software, however it is not transferable into their diagramming software.

11- Once each agencies RP has been chosen, MARK THE LOCATION (RP) and the REFERNCE MEASUREMENT (RM) position so that these locations may be revisited accurately in the future.  Take photos of setup positions with “Area of Interest” in the background, for later positioning purposes if questions arise.

12- Save your Scene work frequently and ALWAYS do a Rough Sketch to compliment work.

13- Each agency RP must use different ‘shot’ number sequence allowing 2,000+ points.

14- Determine GPS coordinates to each RP.  It is possible that one roaming team of an “extra body” or so, could determine a GPS reading for each location.

15- Another “extra body” team, yet with a good understanding of this process, would determine the adequate two (2) MP positions between each volunteering agency using total stations.  Both sets of MP must be within sight of two (2) adjoining Forensic Mapping teams, as seen below.  If possible, maintain 20-30 feet separation between MP’s.

Notice that agency KCSD can see the two MP positions, one set to it’s East and another set of two MP points to their West.  Whereas agency APD for example, can see the same two that KCSD was able to see West of them, and APD can see another set of MP points North of the RP position for GPD, etc. etc.

16- Coordinate all unexpected discoveries with the forensic evidence recovery team.

17- Maintain good communications between prism-pole people and data collector/Instrument operator.  Keep the Codes/Descriptions of evidence simple, yet understandable … keep electronic notes if necessary.

18- Keep in touch often, very often, with whoever is deemed the Lead Agency coordinator.

19- REMEMBER TO TAKE 2^nd REFERENCE MEASUREMENT (RM)

ü  BEFORE POWER DOWN:  Pause to make reasonably sure all evidence & MP’s are documented.

ü  Agencies should participate in a “post-Forensic Mapping” debriefing.  Bring all raw data, their databases, field notes, rough sketches, pics, and all other relevant data.