Archive for the ‘Jonathan McGehee’ Category

Interviewing Techniques and Tips

Saturday, April 10th, 2010



Interviewing is fundamental to many investigations as part of the fact finding process. The goal is to determine the truth about the situation under investigation. A good interviewer should be honest, should be able to empathize with those he is interviewing, should listen well and actively, and should maintain a professional demeanor.


It is said, “Fail to plan and plan to fail.” If a successful interview is to be carried out there should precede some careful planning. Prior to the interview create an outline of specific important questions to ensure they are addressed.


Now we can look at the different aspects of an interview and discuss some of the details pertinent to each part. First comes the greeting. It is important that the interviewer introduce himself in order to establish his professionalism and credibility. Also the interviewer should clearly give the reason for the interview to try and relieve any anxieties the interviewee may have.


Once you have introduced yourself you can begin building rapport. Rapport can be gained with an interviewee by being relaxed and using a comfortable conversational style. Also it is important to be sincere and respectful giving the interviewee the feeling that you are understanding and can be trusted.


After establishing a reasonable degree of rapport you can begin to move into the questioning phase of the interview. It is important to remember that rapport is built and maintained throughout the interview not just at the beginning. Therefore it is important to continue to be professional and somewhat relaxed during the entirety of the interview. That said, the interviewer should maintain a balance realizing the need to maintain control of the discussion and keep focused and on track.

Some tips to remember before beginning:

  • take your time
  • allow periods of silence where necessary
  • avoid compound questions
  • stay neutral, professional, and unbiased
  • do not make assumptions or jump to conclusions
  • do not interrupt
  • questions should start out general and move to specific
  • try not to use leading or loaded questions
  • avoid accusatory questions or statements
  • don’t argue or debate

 A good strategy for the beginning of the questioning phase is to ask open ended questions and ask the interviewee to tell you what happened in their own words. This is called free narrative and allows the interviewee to openly discuss the situation without interruption. To avoid unsolicited, irrelevant responses ensure that the questions, although open-ended, are pointed and address pertinent information. Again maintain control and try to limit digressing by the interviewee. Throughout the questioning you should use good active listening skills and where appropriate give feedback in the form of paraphrasing to ensure you perceive accurately what they are saying. Also show interest with body language and short phrases like, “yes” or “go on.”


After the interviewee has related all the information they have in the free narrative segment you can follow up with direct examination. In this segment you ask more direct questions probing specifics in an attempt to clarify points of vagary in their story or maybe to get them to elaborate where more detail is needed. At this point it may be useful to have the interviewee attempt memory retrieval through what is called a different “channel.” You could ask them about what they heard or what they felt or what they smelled. These different sense cues will sometimes bring to mind something they would not have recalled without the cue. You could also ask them to recall the events in a different order or ask them to explain the events from another perspective. At this point you should also keep in mind any biases that the interviewee may have. You may want to ask a few control questions to help establish the reliability of a particular witness.

Next to ensure accuracy and that they have effectively communicated the information to you, summarize back to the interviewee what it is you have understood about what they have said. This affords another opportunity for clarification and thoroughness. Finally once you have sufficiently gone over the events and understand what the interviewee has said you may wish to cross-examine them. This of course is optional but can be used to carefully explore inconsistent or contradicting areas in the story of events. Once again it is important not to come across with an accusatory tone or to debate the issue but to bring up how there might be some logical problems with some part of their statement. Simply in a neutral tone ask them to help you rectify the apparent inconsistency.


Then once you are satisfied with their statement, feel it is complete, and have a thorough understanding of the events from their perspective, you can close the interview. Ask if there is any other information that you should know about or anything that the interviewee would like to add. Finally thank them for their time and for giving you their statement and reassure them about any concerns they may have.

Jonathan McGehee

Valuable Evidence Collected from Vehicles

Wednesday, March 10th, 2010

As part of a thorough vehicle examination we will first look at the evidence that can be collected from the various lamps on the vehicle. Many times the question arises in an accident about whether or not someone had their headlamps on low or on high beam. Were they using their turn signal? Or were other basic indicator lights illuminated? Sometimes as a result of the collision there may be scientific evidence that may be collected from a bulb or even its remnants that could help answer these question

Second let’s consider the vehicle’s tires. Depending on the circumstances surrounding the accident there may be questions about tire failure. Valuable evidence regarding this can be collected from a careful inspection. Also the tires could be overly worn or improperly inflated and lead to a hydroplaning incident. Or maybe the tires are unevenly worn indicating a possible alignment issue. Also it is important for accident reconstruction purposes to know if the wheels became pinned or locked due to the collision because this affects the post-impact energy-speed calculations.

Next we can look at the damaged areas. When considering vehicle damage it is important to distinguish between contact damage and induced damage. As the terms imply, contact damage is damage to a vehicle caused directly by contact with another vehicle or object. Induced damage is damage that is produced by the collision forces but did not directly make contact with any outside object. Some items of evidence that can be collected from damaged areas include surface abrasions, windshield damage, imprints, tire prints, and paint transfer. Also we want to measure the crush profile and determine the principle direction of force.


Surface abrasions usually result when a vehicle overturns but can result when a vehicle scuffs up against an object or rigid body such as a median wall. When the vehicle slides over a surface it will produce scratches in the vehicle’s paint. The orientation of these scratches can be helpful in determining the movement of the vehicle as the marks are being made.  

With windshield damage it is important to distinguish between induced and contact damage. It is also important to note that some windshield contact damage can result from the deployment of vehicle airbags. If it is determined to be contact damage not from an airbag, it could be from an object outside the vehicle such as a motorcycle or bicycle rider. In this case it would indicate the movement of the rider after the impact with the striking vehicle. The windshield damage could also result from an occupant or some other object inside the vehicle. This information can help determine occupant position and the direction of the collision forces.
Tire prints are similar to imprints however they do not typically leave an impression but a different kind of distinct marking. Sometimes during a collision the tires of one vehicle will rub up against the body of the other leaving a rub mark or tire print. In the case where the front wheel of a semi-tractor rubs up against a vehicle, the lugs can produce circular tears in the metal along with the tire rub mark.




Another bit of evidence that can be helpful in determining the orientation of the vehicles or even which vehicle hit another vehicle at different points in a multi-vehicle accident is paint transfer. Many times paint from one vehicle will be transferred onto the other vehicle where they make contact. Although many times this evidence may be obvious there are other times where it is very miniscule and requires careful examination.

Finally by looking at and taking measurements of the damaged vehicle we can produce a scale diagram of the vehicle and its deformation. This is helpful like the tire prints and paint transfer in determining the way the vehicles came together in the collision. Also it can sometimes be used with crash test data to determine an impact speed for the striking vehicle. Also we can look at different components of the vehicle that were displaced during the collision and take note of the direction of their displacement from their original placement to get an idea of the principle direction of force that was applied to the vehicle. This can be helpful in confirming other calculations and in understanding occupant kinematics.


This article is not exhaustive but serves to highlight the fact that a lot of valuable evidence and data can be obtained from a careful vehicle inspection. This information can assist in answering questions that arise when investigating the causes of vehicle accidents.


Jonathan McGehee



The Value of Demonstrative Evidence

Thursday, September 3rd, 2009

Quality Photographs

As the saying goes, a picture is worth a thousand words. Well a picture serving as demonstrative evidence is equally powerful. It enables the investigator to document all aspects of the scene, vehicles, and any other valuable evidence for future reference and analysis. Additionally it enables others such as claims adjusters, lawyers, other investigators, juries, and judges to examine the scene, vehicles, or other evidence for themselves.

In regard to this last point, it must be emphasized that the photographer needs to be knowledgable about how to take accurate photographs that are true representations of the evidence. Care must be taken in the use of special lenses or filters that may distort the perspective or appearance of the shot. However, as long as proper equipment and techniques are used, a photograph generally tends to be considered irrefutable evidence.

Scale Diagrams

A scale diagram is another useful piece of demonstrative evidence. Assuming it is based on accurate measurements of the scene and vehicles, it can be used to very accurately depict locations and speeds of vehicles at different times as the vehicles approach and depart from the area of impact. Also line of sight or other important characteristics of the particular accident can be represented graphically to enhance understanding. These diagrams are helpful to the reconstructionist for doing analysis and calculations. They are useful to other interested parties to be able to visualize how the accident occurred and to understand the reconstructionists conclusions.

Animations and Simulations

Finally we will look at animations and simulations. Due to the advances in computer technology we are now able to generate these pieces of demonstrative evidence that are arguably the most advanced and self explanatory available. Although it may be self-evident we will define the difference between an animation and simulation. Both are videos generated from a series of either two-dimenisional or three-dimensional shots that show the vehicles moving through space and the accident sequence. However, the movement of an animation is completely directed by the animator whereas the movement of a simulation is generated by a computer program designed to replicate how a vehicle would move, react, and deform in an accident scenario in the real world. This algorithm is of course then based on general principles of engineering and physics. The animation allows the reconstructionist to put together his entire analysis, calculations, and measurements into one package and via this video show how the accident occurred. Simulations, assuming the algorithm is sound and propertly applied, are useful for testing theories and analysis. Click below for an example of each:



Jonathan McGehee

Contributing Factors: The T-Bone

Friday, November 7th, 2008

There are a wide variety of contributing factors associated with vehicle accidents, and careful analysis is required to fully and accurately determine fault because of these many factors. For instance, let’s consider the case of a “T-Bone” type collision.

In this hypothetical collision, there is a Chevrolet traveling south on Hwy 11 when a Nissan pulls out from a side road into the path of the Chevrolet, and the Chevrolet impacts into the passenger side of the Nissan. Who is at fault in this collision? That can depend on several factors. Below is a partial list of possible contributing factors for each vehicle.


Nissan Chevrolet
Disregarded a Stop Sign Speeding
Failed to Yield the Right of Way Inattentiveness
Headlights Not Illuminated Headlights Not Illuminated

Only through a careful and thorough investigation can fault be accurately assigned. Our accident reconstructionists can typically confirm or disprove which of these were in fact the cause(s) of the accident. The following are various questions about contributing factors that you might have and the corresponding methodology we have available to answer those questions.

Question: Did the driver disregard the stop sign?

Answer: Based on impact speed and acceleration calculations we can determine whether it is reasonable for a vehicle to reach its speed after stopping at the stop sign.

Question: Was the vehicle speeding?

Answer: We can do various calculations to determine speed based on damage patterns, departure angles, and final rest locations. Also, we may be able to download crash data recorder information that can answer this question.

Question: Was the driver paying attention?

Answer: Based on speed/time/distance calculations, we can determine the approximate location where and the time when the driver perceived the hazard of the other vehicle and began to react. Then, we can attest to whether or not this information is consistent with a typical and attentive perception and response.

Question: Were the vehicle’s lights on?

Answer: In most cases this can be determined by forensic evidence that can be documented and collected.

Other questions that we consider and have the ability to analyze and address include:

· Was fog present creating a sight distance and headlight issue?

· Did sun glare obstruct or limit the view of the driver?

· Were the ambient light conditions such that the vehicle would have been visible?

· Were the proper traffic controls in place and appropriately located?

· Did the environmental conditions call for a reduction in the reasonable speed to be traveling?

As you can see, it is not a simple matter to say one or the other party is at fault. It takes a conscientious consideration of many possible factors.

Jonathan McGehee

Preserving the Accident Scene

Monday, July 7th, 2008

Consider yourself in the following scenario: You contact us to investigate an accident that occurred a year ago. We arrive at the scene. We attempt to gather evidence, but there appears to be no evidence to collect. There are no skid marks, no gouge marks, no fluid spills and the road is repaved. Trees may have been cut down or trimmed. Road signs have been moved. The vehicles are gone, nothing was marked, and the police did not take any photographs. We attempt to locate the vehicles to inspect their damage and find that they have been repaired or salvaged. As you can imagine, our ability to replicate this incident has become increasingly difficult.


The previous example is extreme, but nevertheless emphasizes the importance of preserving evidence as soon as possible. In accident reconstruction, our analysis can only be as accurate as the evidence we gather. As time goes on the evidence degrades, and as the evidence degrades so does the ability to determine what happened with certainty. This fact puts us continually fighting against the clock because a significant amount of scene evidence is short-lived and fleeting. For instance, impending skid marks, ABS skid marks, debris patterns, and paint transfers are typically moved or nowhere to be found within a few hours or days.


After Longer Periods of Time the Following Can Also Be Altered or Removed:

  • Roadway Signs (especially in construction areas)
  • Roadway Drag Factor (further traffic degradation or re-pavement)
  • Sight Distance Obstructions (embankments, trees, parked vehicles, etc.)

This is just a partial list but it stands to emphasize the point.


When an accident occurs, consider the benefits of taking timely action.  Ideally we would be able to respond to the scene immediately after the original incident, especially if there is any indication that a comprehensive, professional investigation may be required. This gives us the opportunity to document the scene thoroughly and accurately.


We utilize various methodologies and technologies to document the scene including:

  • Quality Digital Photography
  • D.A.R.T. LX-2 Drag Sled
  • Crash Data Retrieval System
  • Sokkia Total Station
  • Nikon Reflectorless Total Station

VCE has been utilizing the Sokkia Total Station to measure accident scenes with great accuracy and precision for over 10 years. This instrument allows you to measure points at the scene in a three-dimensional framework based on distances and angles to produce X, Y, and Z coordinates that can be used with our software programs to create precise two-dimensional and three-dimensional scale diagrams, animations, and simulations. Just recently we have expanded our services to include a Nikon Reflectorless Total Station that allows measurements to be taken without the necessity of a reflector pole. This is a great asset when attempting to take measurements of a busy intersection or interstate where it would be impractical to stand in the roadway with a reflector pole. Furthermore it is ideal for measuring damage profiles of vehicles.


With our thorough scene investigation complete, the scene and evidence are recorded and saved. The facts of the particular case can be preserved for whatever future analysis might be necessary. With this information, you can make an informed decision about the requirement of further investigation based on our initial findings without the additional pressure of capturing the evidence before it is gone.


Jonathan McGehee