Choosing the “best” R.P. Location(s)

By Mick Capman,
PSFM President (Kalamazoo County Sheriff – Retired)

As you arrive, try to find the first officer to have arrived at the scene, a supervisor or the Crime Scene Tech to discuss with them (while examining the scene yourself) among other topics, what is the “nature of the crime”, how extensive size-wise is the scene and where relevant physical evidence is at and how it is currently marked for ID purposes. 

As you take this scene tour, you could be making your Rough Sketch too.

From first knowing the expansiveness of the scene and where the “focus” is of the scene itself, you will have a better ‘feel’ for where-best to position your total station (aka: ReferencePoint/RP) in order to 1)rule out any vision obstructions, and 2)document as much as possible from as few RP’s as necessary.  Repositioning or moving the RP is a topic covered elsewhere.

For example, as seen here the “focus” was the relevant physical evidence seen on the roadway surface (skid mark) and the location of a nearby house to the intersection, specifically a certain window facing said intersection. 

~ Make This Process Easy on Yourself ~

Once these issues are learned, then positioning the total station (RP) should be from a position of “comfort” for the Instrument operator. 

Rather than position it such that the Instrument operator has to physically move or turn left, right, and behind themselves (getting cables all tangled up and possibly kicking the tripod stand) ~ position it, as suggested here, from across the street where long-term, physical movement is limited and ‘forward-only’ sighting/aiming is increased.   Thus, “Making This Process Easy On Yourself!”    Of course, there will be types of scenes and situations where time constraints plus having the scene totally “yellow-taped” will permit you to position the RP where ever the heck (!!) you want.

The below two scenes illustrates “Scene Focus of Interest” areas from just one of numerous RP’s.  Captured were certain physical features unique to the scene, distance and ‘shooting-cone positions of opportunity’ and/or physical evidence that was observed over a wide                       

Crime Scene documented by east coast PD

Again, good thoughts to consider include, as it relates to the RP placement- learn the ‘nature of the crime’, walk the scene, and where possible, choose to position the RP over a something of a “permanent” nature, i.e. manhole cover, fire hydrant or scribe/mark/drill/paint the precise location (as seen here).

 

Whether in an enclosed parking ramp, underground tunnel, or an open field (GPS & metal stake) a RP location can easily be self-made/marked.

 

Another very useful feature of the modern total station is its ability to measure to certain points of evidence (surfaces) using “reflectorless” (aka: Prismless) technology!!!  This feature (new since roughly 1999 in the U.S.A) combined with a built-in red laser pointer (!!) further permits tremendous FLEXIBILITY in how and where you choose to position your RP!!

In some cases, forget about having to 1) focus on the ‘target’ (evidence) and 2) having to position the Instruments ‘face-plate’ to the operators ‘sternum’ height!  Nearly any height will do, and usually NO focusing necessary!!

Troopers from OH State Hwy Patrol using ‘Prismless’ Instrument at max-height.

This isn’t just about a manufacture of total stations that sell “reflectorless” technologyIts much more than that…. 

Its about Sokkia (generally) & Leica who have additionally incorporated a RED DOT, just like a hand-held laser pointer, to their internal ‘reticle’ so that generally especially under low light conditions, an operator can visually see where the Instruments precise cross-hair is aimed …by just looking for the RED aiming DOT!!   Too simple … and very handy (if used safely)!!!

We have used this method successfully for

…documenting a fires’ burn pattern at a recent arson(see next diagram), on side walls and ceiling area where there was no power for interior lighting, it was a total blackout situation and flashlights were necessary,

… documenting a drive-by shooting scene on a neighborhood 2-ln. street where 100% of the scene, including a reluctant witness residence across from the victim’s house, was documented “reflectorless” with the RED aiming DOT,

… documenting a vehicles’ crush pattern while it was parked at an indoor impound area,

… documenting a suspicious occurrence in a multi-leveled interior of a parking garage,

… documented a interior ground floor booking/receiving area of a county jail with nearly 20 RP’s stemming from a departments’ internal investigation,

… documented a motorcycle-car fatal on a busy highway, etc. etc.

 

This process can totally be a one-person operation for distances generally within 1,000+ ft. (!!)of the identified physical evidence.

This process then changes, among other considerations, the types of scenes to document and how much other scene data (detail) is documented.

      Nearly any side interior room.                              Nearly any viewable crush configuration.

                      

For documenting a vehicles’ crush/damage profile, most Crash Reconstructionist position the RP 25-30 feet away from vehicle.   

This is still a good technique.  One should also, like walking the crash scene to get a “feel” of the issues at hand, walk up to the vehicle and examine closely the overall pattern (folded sheet metal, frame deformation, etc.) of the ‘contact’ and ‘induced’ damage area.

Some crash reconstructionists’ aid their “reflectorless” documentation abilities by placing white in color, dime-sized circular stickers where they wish the ‘shot’ to be collected.  The RED DOT can nicely be seen using this technique under most circumstances. 

And if necessary for reconstruction and comparison purposes, the visible white-dot stickers, as seen in above digital photo, make it easy for the user to further understand the crash dynamics and articulate, if possible, the sequence of events.

Reflectorless total station technology, combined with the ability to SEE “live” the consequences of each ‘shot’ taken, and the power to present the scene of any size and configuration in something beyond 2D ~ but instead  in REAL 3D  ~ is invaluable.     

 
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