effects and bias in crime reconstruction

Welcome to Basic Crime Reconstruction. Reconstructing a crime is not a magical process or the result of some supernatural insight that is available to only a select few. Rather, it is the result of pain-staking forensic investigation and logical deduction. This course will not make you a crime scene re-constructionist. What it will do is to help you take all of the factors including forensic evidence, witness statements, suspect statements, and other evidence; and enable you through the process of logical deduction to sequence the events involved in the crime.

I. What is Crime Scene Reconstruction?

We are going to focus on something we call holistic crime reconstruction. As defined by W. Jerry Chisum and Brent Turvey in their book “Crime Reconstruction”, holistic crime reconstruction “is the development of actions and circumstances based on the system of evidence discovered and examined in relation to a particular crime.”

As part of this type of reconstruction we're going to focus on all aspects of the crime. The shortcoming of many crime reconstruction methodologies is that they focus on only one aspect of the evidence such as forensics or witness statements or the suspect statements, etc.. The idea behind holistic crime reconstruction is to bring together all of the information about a particular crime and to use all of that information in the reconstruction. You must treat all items of information involved in the crime as interrelated.

II. Forensic Technicians, Forensic Specialists, and Forensic Generalists

A. Forensic Technician – A forensic technician is trained in specific procedures related to collecting, packaging, labeling, and even performing some tests at the crime scene. As long as the technician knows how the task should be performed, there is no real need for them to understand the scientific method or the greater principles of forensic science.

B. Forensic Specialist – A forensic specialist is someone who has extensive expertise and training in the analysis of physical evidence in a particular specialty area. An example of this would a fingerprint examiner in a laboratory or a ballistics expert. They normally are employed in a crime laboratory and not out on the street like a technician.

C. Forensic Generalist – A forensic generalist is broadly educated and is trained in a variety of forensic specialties. He is a broad picture guy – not an absolute expert in any one area, but has considerable expertise in many different areas. In fact, you could say that his major area of expertise is in the interpretation of evidence and how it fits into the crime puzzle.

III. Crime Reconstruction as the Culmination of a Process – The reconstruction of a crime is the last step in a long and methodical process that each piece of evidence/information goes through. The steps in this process and who is normally responsible for the evidence at each step are:

A. Recognition (detective/investigator/forensic technician) – This is the recognition that a piece of material or information is evidence related to the case.

B. Preservation (detective/investigator/forensic technician) – This is where the necessary steps are taken to preserve the evidence or information.

C. Documentation (detective/investigator/forensic technician) – The necessary photos are taken of the evidence and the necessary notes made.

D. Collection (detective/investigator/forensic technician) – The evidence is collected and appropriately packaged and labeled.

E. Transportation (detective/investigator/forensic technician) – The evidence is transported to the evidence locker/property room or to the crime laboratory ensuring that chain of custody is preserved.

F. Identification/Classification (forensic specialist) – This is the practice of categorizing the evidence according to its characteristics such as weight, color, chemical composition, etc. An example of this is when the lab identifies the white powder as cocaine.

G. Comparison (forensic specialist) – This is the examination of two or more items to establish similarities and dissimilarities between them. An example is when you ask the lab to compare a latent print to known fingerprint.

H. Individuation (forensic specialist) – This is the establishment of the uniqueness of an item through examination and experimentation to show that no other item is exactly like the item in question. An example of this would be the DNA analysis of a blood drop showing that it could not have come from any one other than the person it matches.

I. Interpretation/Reconstruction (forensic generalist) – This is where the significance of the evidence or information is determined and how it fits into the puzzle that is your crime.

Even though the above listed process is primarily slanted towards physical forensic evidence, many of the steps also apply to information such as witness testimony that also helps you put together the puzzle.

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