Forensic Psychology: Guide to Crime Scene Investigations
The history of crime investigation is one of increasing sophistication. Couple this with a forensic psychologist’s need for accuracy, transparency, and efficiency and it is plain to see why crime scene investigations are, now more than ever, so important. The FBI’s Fingerprint Identification pamphlet states that, although fingerprints were already known to be unique to individuals by the time they were first cataloged in the early 20th century for the purpose of identifying prisoners, the increasing usefulness of fingerprints in linking suspects to a crime resulted in the first national repository of prints in the 1920s. This was one of the earliest signs of the increasing power and complexity of crime scene investigations in the 1900s, a century that would end with another major innovation: DNA evidence. According to the Human Genome Project’s website, all 50 states now maintain registries of DNA samples. The link between science and criminal justice is stronger than ever.
Crime scene investigation today is a calling that requires all the cunning and common sense of the old days combined with a knowledge of modern science and law. There are almost as many pamphlets, guidebooks, and bulletins about investigating crime scenes as there are local police departments and federal law enforcement agencies, so the majority of the resources gathered on this page are PDF versions of official publications, and have been selected for their thoroughness and authority. The two main sections cover investigative procedures and the handling of evidence, although there is much overlap in content between the two. Together, they exhibit the vast amount of specialized knowledge that goes into a criminal investigation, and how specialists from a wide range of fields can work together.
Procedures and Practices
According to the U.S. Department of Justice’s Crime Scene Investigation handbook, the first order of business when officers arrive on a crime scene is to secure the area around the scene and prevent any disturbance of the evidence. Witnesses and bystanders, as well as other officers, are often responsible for the contamination of a crime scene. At the same time, investigators should document the time of their arrival and report it, look for secondary crime scenes and witnesses (or fleeing suspects), and ensure the safety of other officers and investigators. Once the actual investigation begins, officers can expect to engage in the following tasks:
- Containment: Identifying and apprehending anyone found on the crime scene, preventing bystanders or others from entering the area, keeping a lookout for substances or people who may endanger officers or others, providing emergency care for victims, marking the boundaries of the crime scene, and so on.
- Documentation: Recording the removal of evidence from a crime scene or its movement within one, the time that investigators arrive, the type of evidence, its location, and who found it, and the transfer of evidence to a laboratory.
- Photography: Documenting a crime scene at a given point during the investigation, which requires both cameras and specialized lighting equipment.
- Sketching: Illustrating the placement of evidence, victims, and other objects on a crime scene for juries and investigating officers, especially when a photograph is insufficient or too complex.
This section includes at least one useful source for each of the main procedures in crime scene investigations described above, although additional procedures, such as investigating human remains and questioning witnesses and neighbors, are covered in some of the more general resources.
- Crime Scene Sketch is the fourth chapter of the Wisconsin State Crime Laboratory’s Physical Evidence Handbook, covering floor plans, sketches of actual crime scenes, decisions about scale, proper equipment, and the use of computer-generated images. The chapter takes the reader through these topics step-by-step, providing multiple full-color illustrations.
- Crime Scene Photography Tips & Techniques, from Forensic Enterprises, Inc. organizes its advice by the type of equipment used, including Laser/ALS sources, flash photography, digital cameras, and so on. Each links to a separate article written by Hayden B. Baldwin, a retired police sergeant.
- Recording Legible Fingerprints is only part of a comprehensive description of fingerprint processing by the FBI, which uses the sophisticated Automated Fingerprint Identification System (IAFIS). Associated articles include a Fingerprint Identification Overview and a Capturing Legible Fingerprints guide.
- U.S. Department of Justice: Crime Scene Investigation is a 58-page manual prepared for law enforcement institutions and departments of corrections all over the U.S. The document covers response, safety, containment, jurisdiction, documentation, and many other topics and includes several appendices: a glossary, bibliography, and list of organizations.
The Physical Evidence Manual of Oregon States emphasizes, above all else, the safety of investigators and bystanders and the integrity of the evidence. In particular, the document advises investigators to be open to multiple types of evidence (some of which are described below), to properly mark, label, and document every evidence sample, to keep articles of evidence separate from one another with proper packaging and sealing, and to use the proper packaging and equipment so that evidence does not become contaminated. The following are some of the types of evidence that investigators examine in detail:
- Ballistics: Investigators look for evidence created by firearms, especially the direction of bullets and the angle at which shooters fired.
- Bloodstain Patterns: Investigators look for the impact stains (including angles of impact), drip and flow patterns, and transfer media (shoes, fingerprints, etc.) of blood. Finding blood can also lead to DNA evidence.
- DNA: Investigators look for organic materials, including blood, hair, fingernails, skin, and so on, that contain enough genetic material to profile suspects, victims, or witnesses.
- Fingerprints: Investigators look for fingerprints, which are unique to every individual, by “dusting” with a fine powder (such as chalk and graphite) or by using electronic methods.
- Hair: Investigators look for hair samples, which have unique properties based on the species, ethnicity, and part of the body from which they come.
Some other kinds of evidence processed by investigation teams that are described in the resources below include glass fragments, soil, shoe impressions, documents (including computers), paint, and narcotics. Bulletins on each of these topics can be found on the Crime Scene Investigator Network.
- Ballistics: The Science of Guns, by Katherine Ramsland, is a 6-chapter overview of how the investigation of firearms, bullets, and bullet holes have assisted in investigations throughout history. The article is part of the Tru TV Crime Library section, “Criminal Minds and Methods.”
- DNA Forensics is a part of the Human Genome Project and provides information about the legality, uses, and procedures of DNA evidence. Numerous links to law enforcement and journalistic sources follow the lengthy article, although other links can be found throughout. Most notably, the page maintains a list of DNA databases.
- Evidence Collection Guidelines, a section within the Crime Scene Investigator Network, lists proper procedures for the analysis of blood, semen, hair, fibers, glass, paint, volatile substances, ballistics, marks made by tools, narcotics and prescription drugs, documents, and fingerprints. Each evidence type is followed by a series of quick and accessible bulleted points.
- Forensic Fiber and Hair Evidence Analysis is a 4-page bulletin created by the Indianapolis-Marion County Forensic Services Agency. The document begins by discussing types of cases in which hair analysis is important (rape, burglary, homicide, etc.) and then gives step-by-step instructions for collecting and investigating different kinds of hair (head hair, animal hair, etc.).
- The International Association for Property and Evidence, Inc. offers classes and licensure for students or investigators interested in becoming classified as Certified Property and Evidence Specialists. The organization also publishes The Evidence Log, some articles of which can be read on the website.
- Physical Evidence Manual, published by the Oregon State Police, is one of the more comprehensive state-sponsored handbooks about handling evidence. A section on basic evidence covers packaging, sealing, custody, delivery, and proper documentation. Other sections discuss special procedures for arson crime scenes, biological evidence (blood, saliva, etc.), and controlled substances. Finally, the book closes with a discussion of these different kinds of evidence.
Two kinds of websites are gathered in this section. The first type is professional organizations that can connect visitors to additional resources or provide training for students interested in becoming forensic scientists, crime scene investigators, or other specialists. The other kind of website is large web portals, such as the Crime Scene Investigator Network, that specialize in providing information in the form of news, official guidebooks and pamphlets by law enforcement institutions, and tutorials.
- The Association for Crime Scene Reconstruction was established in 1991 to provide a medium of communication between the various professionals involved in crime scenes and educators so as to help investigators gain a better understanding of the big picture. Besides serving as a forum for information exchange (through conferences), the organization also offers training, maintains a job board, and provides a list of links.
- Crime and Clues is a broad-based resource that provides news and educational articles on different kinds of evidence: behavioral, demonstrative, digital, legal, physical, and testimonial. Sections on crime scene investigations and training are also provided, as is an online store.
- The Crime Scene Investigator Network compiles documents from law enforcement agencies, especially police departments, from all over the U.S. and organizes them by topic: “Crime Scene Response,” “Evidence Collection,” “Scene and Evidence Photography,” and so on. Articles from scholarly journals, educational information, and advice about careers can be found on the website as well.
- Forensics Enterprises, Inc., directed by retired police sergeant Hayden B. Baldwin, provides services as forensic consultants and crime scene instructors, but also hosts a detailed body of crime scene investigation information on the website. Sections on photography, proper protocol, documentation, handling bodies, and dealing with bio-hazards are available.
- Forensic Magazine organizes its news and editorials with tabs along the top of the screen, including “Crime Scene,” “Crime Lab,” “DNA,” “Legal Process,” and “Forensic Science.” Videos, tips, and a buyer’s guide are available as well. The website labels some of its features by how they might be used by the reader, including “Crime Scene 101” and “Case Study” articles.
- The International Crime Scene Investigators Association primarily exists to help investigators and law enforcement agencies around the world, but its website is a wealth of information about the education and training necessary to become a CSI, the equipment used in investigations, and career paths. Numerous links are presented on the website as well, organized by topic (photography, sketching, etc.).