Introduction

Evolving crime scene technology and methods, such as genetic genealogy and 3D crime scene scanning applications, are rapidly improving the capability and importance of forensic science. To effectively use these technologies, officers must properly define the crime scene, scan the area, and collect the evidence.  These actions “play a pivotal role in the resolution of a case. Careful, thorough investigation is key to ensure that potential physical evidence is not tainted or destroyed, or potential witnesses overlooked” . From a simple entering auto to a multiple casualty homicide, the steps for documentation, identification, collection, and reconstruction of a crime scene are the same.  This methodology is simply scaled to the complexity of the scene.

Responding to and Securing the Scene

The initial steps taken by first responders upon arrival at an incident scene can often set the tone of an investigation.  First responders’ priority is to render a scene safe and provide medical aid to victims.  Maintaining the integrity of physical evidence is a secondary concern. Still, simple steps can be taken to protect the scene and evidence.  For example, crime scenes are commonly secured using crime scene tape, traffic cones, barricades, police vehicles, posted officers, or simply locking a door (no one wants customers entering a business that has just been robbed). Crime scene protection that may not warrant barricades, such as an entered automobile, can include having victims to not touch their vehicle or items removed from the car that are found on the ground.   

Getting Back to the Basics

Edmond Locard’s “Principal of Exchange” holds that during the commission of a criminal act, certain physical items and other evidence may be deposited in the scene.  “Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him… Physical evidence cannot be wrong, it cannot perjure itself. It cannot be wholly absent. Only human failure to find it, study and understand it can diminish its value” (Kirk, 1953).  It is easy for an officer to become complacent with some types of crime scenes (e.g. entering autos, burglaries) and simply go through the motions of collecting and reporting information. As the type of evidence to be collected becomes less common, such as DNA, officers tend to pay less attention to locating and collecting it.

To avoid this, officers must first display the diligence and initiative to search and look for evidence. Once the evidence is identified, they must have the skills to properly collect and store the evidence. Just like an officer’s marksmanship skills, the ability to potentially locate evidence, dust for fingerprints, photograph a scene, and other investigative actions are perishable skills.  Because of this, it is important for the officer processing a scene to acknowledge the need to continuously hone their skills to not only identify and understand each evidentiary item but capture the scene with jury presentation in mind.

   

Scene Documentation

Proper documentation enables a jury to be transported from the courtroom back to the crime scene, provides recall for investigators after the fact, and provides critical information to conduct a post scene analysis of evidence.  “Crime scene reconstruction begins with a systematic, meticulous, and competent endeavor by the crime scene processing team” . While advanced concepts of crime scene reconstruction, such as bloodstain pattern analysis or flight path determination in shooting incidents, may not be warranted in property crime cases, the analytical approach that reconstruction takes is still pertinent.

Documentation can be divided between three categories: written notes, photographs, and diagraming.

Written Notes: Written notes of the observations in an incident report convey information that cannot be easily depicted.  To accomplish this, reports must go beyond simply establishing the elements of the crime.  Victim statements, the ambient temperature, and odors within a scene are all examples of the details an investigation can hinge upon.  The scene should be described in a manner so it is easily understood how it was found prior to the alteration inherently caused by public safety. To accomplish this, evidence should be clearly described, and its location noted.

Photographs: Since most people are visual learners, crime scene photography is critical for creating a historical record of the crime scene.  Two types of photographs should be taken during every crime scene investigation: crime scene photographs and ‘examination quality’ photographs.  Crime scene photographs depict the scene and items within the scene.  Each item of evidence should be portrayed through three perspectives, including an overall shot, medium range shot, and close-up photograph.

The overall or wide-angle photograph establishes where the viewer is located and all the items within the context of that area.  For example, in an entering auto case, this would depict the entire vehicle and where it is parked.  The second, the medium range photograph, is closer to specific items of interest.  Within this angle, the photographer is representing the spatial relationship of certain items of evidence to one another.  In the case of the vehicle, the images may depict the front passenger door, with a broken window, glass on the ground, and a developed fingerprint on the door handle.  The last photographs are images in which the photographer is as close as possible to clearly depict the details of a specific item of evidence. This is done without and then with a scale in the photograph.

‘Examination quality’ photographs should be taken of any evidence with patterns or other details that can be analyzed from the photograph (e.g. fingerprints, bloodstain patterns, shoe and tire impressions, tool marks, and bullet defects).  An ‘examination quality’ photograph enables an examiner to retrieve critical evidence measurements and data directly from the photograph without having to be present at the crime scene.  The ‘examination quality’ photograph requires two key components; a scale must be included within the photograph and the photograph must be taken ‘straight down’ / 90-degree angle of the surface.  These photography principals should be followed on every scene where evidence is collected.   

Diagraming:  Another necessary method of representing the scene and the evidence is the task of mapping or diagraming the location. Since most traffic collision reports require a diagram, officers are very familiar with this concept.  The same principal applies in non-traffic cases. A crime scene diagram is an effective tool to visually represent the spatial relationships of evidence within the confines of the scene.  This includes measurements needed to triangulate the location of evidence so the scene can be easily and correctly recreated. Photographs often include non-evidence items that “clutter” the images and detract from the focus on the critical pieces of evidence.  Diagramming enables the officer to draw the jury’s eyes to only the important aspects (i.e. evidence) within the crime scene. The details of a diagram can be scaled according to the needs of the case. For example, to represent the location of a fingerprint is much different than the complex representation of multiple bloodstain patterns’ orientation.  For more serious investigations, the utilization of 3D laser scanners are an almost necessity in 21st century criminal investigations. The data collected and time on scene saved by this type of equipment is unparalleled by any other investigative tool.     

  

Processing the Scene

Crime scene investigations are a running checklist, requiring on-going prioritization of evidence and investigative acts.  After the scene has been properly documented and an evidentiary search conducted to identify items of evidence, areas to process for latent print and/or DNA evidence can be completed.  Evidence of a sensitive nature, that can be affected by time or environmental factors, should be collected as soon as possible.  After the processing of all further evidence has been completed (fingerprint processing, DNA sampling, trace evidence lifts, impression casts), the items can be collected and packaged.  In general, the utilization of personal protective equipment (PPE) should be required of staff while on scenes or handling evidentiary items.  However, when collecting DNA evidence, the investigator should change their gloves between each sample as well as wear the proper personal protective equipment to minimize possible contamination of the samples.

Whenever possible, it is preferable to process evidence at a lab, as opposed to processing it at the scene.  Biological evidence or items that may require DNA or blood examinations should be packaged in breathable containers (e.g. paper bags or cardboard boxes).  Once all procedures for correct packaging have been utilized and secured within the agency’s property and evidence section (not a Detective’s desk drawer), the evidence can move forward for further examination.

Quality Controls

To ensure every victim is receiving the absolute best investigative services possible, leaders throughout the organization must review officers work to ensure it complies with established policy. Periodically, other reviews should
be made of the agency’s policies for the processing basic crime scenes as well as their quality control process to ensure they are up-to-date and are being followed. For example, an agency provides every officer with a patrol fingerprint kit and training to identify, develop, and collect fingerprints.  Five months after the program’s implementation and audit revealed officers collected and submitted evidence for examination in only 7 out of the 143 (4.89%) reported entering autos and burglaries. Once this problem is identified, it is important to determine if it is an issue with policy, training, supervision, or reporting and take the appropriate corrective action.

Conclusion

Police agencies’ fundamental purpose is to protect and defend the community and its citizens. As a profession, we are past the days of simple investigative approaches. Advances in forensic science have enabled agencies to better achieve conclusive evidence of what occurred at a scene as well as more effectively identify the suspect. Essentially, officers need only collect one nanogram of genetic material to positively identify an offender.

At the same time, television portrayals of police officers have led many of our citizens to expect officers to take the time to collect this evidence.  The first step to meeting these expectations is to follow the fundamental steps to identifying the crime scene, scan the area to identify evidence, photograph/diagram the scene, and properly collect and store the evidence for processing.

References:

Kirk, P. L. (1953). Crime Investigation. New York: Interscience Publ.

Ogle, R. R. (2012). Crime Scene Investigation & Reconstruction (3rd ed.). Upper Saddle River, NJ: Pearson – Prentice Hall.

 

 

Detective Zack Kowalske has served with the Roswell Police Department since 2009.  The majority of his career has been within the Crime Scene Investigations Unit.  He is a board-certified Crime Scene Reconstructionist, specialist in bloodstain pattern analysis and shooting incidents, and PhD Researcher and Student at Staffordshire University.  He may be contacted at zkowalske@roswellgov.com.