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Criminal Investigation: The Lost Art - Page 2 of 3



  • Start every case with the expectation of solving it.
  • Until the evidence points to a particular suspect, keep an open mind.
  • Remember, just because you believe something, doesn’t make it true.
  • Eliminate the most plausible account of the crime before embracing the less likely scenarios.
  • Make sure that your theory of the case makes sense, that is logical.
  • Keep personal bias out of your investigative thinking.
  • When having difficulty solving a case, consider different points of view.
  • Understand that physical evidence is generally used to prove the case after it has been solved. The process of solving a case and proving it are different tasks.
  • Know the difference between direct and circumstantial evidence and the strengths and weaknesses of each. (Circumstantial evidence, particularly in the form of physical clues, can be very reliable and persuasive evidence.)
  • Understand that while certain types of people may appear on the surface to be unlikely suspects because of who they are, no one should be ruled out solely on the basis of their high status or reputation in the community.
  • Understand that facts and evidence are not necessarily the same as the truth, and as a criminal investigator, you are after the truth.


  • Learn how to recognize, preserve, handle, package and mark physical evidence.
  • In gathering crime scene evidence, use the rule of inclusiveness.
  • Understand how the Locard Exchange Principle applies to crime scene evidence. (Edmund Locard, the scientist who started the world’s first crime laboratory in l9ll in Lyons, France, was the first to articulate the notion that at least in theory, a criminal will leave part of himself at the scene of the crime and take a piece of the scene with him.)
  • Keep the number of crime scene processors to no more than two or three.
  • Make crime scene sketches that include accurate measurements.
  • Take plenty of crime scene photographs, there will not be another chance to do so.
  • Maintain sole custody of the evidence you have recovered until it is turned over to crime lab personnel, thus avoiding chain-of-custody problems.
  • Absent special circumstances, conduct crime scene investigations in daylight.
  • Through the interpretation of crime scene evidence, for example, blood splatter analysis, bullet holes, and various kinds of impression evidence, figure out (reconstruct) what had taken place at the crime scene.
  • Be alert to the possibility that the crime scene has been sanitized or in some way altered by the criminal.


  • Develop an investigative plan that includes a list of specific questions that will have to be answered before the crime can be solved.
  • Learn how to formulate and prioritize, on a case by case basis, investigative leads.
  • Keep lists of leads that have been covered and ones that have not.
  • Periodically review the case for fresh and missed leads.
  • Maintain a detailed chronology of the crime that includes the activities of suspects, witnesses and key events leading up to and through the event.
  • Keep a detailed hour-by-hour, day-by-day journal of your investigation.
  • Maintain a directory of every person associated with the case that includes their phone numbers, addresses, e-mail, occupations, and relationship to the case.

LEADS (Things to do that furthers the investigation.)

  • As you become familiar with more and more investigations, yours and others, mentally catalogue the ways in which cases are solved (not proven) such as a sharp observation, a critical interview, an anonymous tip, the finding of a particular document, a revealing piece of background information, an offhand remark, or a flash of deductive insight (connecting the dots).
  • In crimes that have distinctive characteristics, so-called signature crimes common to serial killing, arson and bomb cases, look for similar MOs in other cases that may have been committed by the person you’re trying to identify.
  • In homicide cases, consult studies that reveal statistical likelihoods. For example, in a case involving the stabbing death of a l2-year-old girl in her bedroom, what are the odds that the crime was committed by her l6-year-old brother compared to her parents or others with the opportunity to commit the crime.
  • Remember that a large percentage of criminal homicides involving adult victims, are either motivated by anger, sex, or money.
  • Remember that burglars, rapists, arsonists, and killers usually commit their crimes not far from where they live.
  • Remember that because criminals are not good at keeping secrets, if you talk to enough people you will likely break the case.
  • Remember that robbers often hit the same store more than once.
  • Remember that killers dumping bodies do so in nearby water or in remote areas in which they have had some familiarity.
  • Remember, in arson cases, if you don’t know exactly where the fire started, there is no way you can establish that the fire was intentionally set, the corpus delecti of arson.
  • Remember, in arson investigations, learn to interpret the basic smoke, burn, and heat indicators that will help determine the origin, cause and intensity of the fire. (See the list of smoke, burn and heat indicators attached to this document.)
  • Know the general signs of arson, and when a fire, in movement and intensity, is abnormal or unnatural. (An abnormal fire pattern suggests the presence of an accelerant.)
  • Remember that most serial arsonists set fires for the pathological reasons of rage, revenge, attention, thrill, or sexual gratification.
  • Remember that cars, SUVs, vans, and pickup trucks are rarely destroyed completely by fire. A high percentage of these fires involve arson motivated by insurance fraud.
  • Canvas the neighborhood of a crime for possible witnesses. Make sure every resident is interviewed.
  • Get to know the various public and private repositories for information ranging from credit data to birth records.
  • When calling on the services of a polygraph examiner, use qualified independent practitioners who have no stake in the results.
  • Be extremely skeptical of information that has come from so-called “recovered memory.”
  • Be skeptical of information derived from forensic hypnosis.
  • Remember that children, even very young ones, will lie, particularly when they are sexual abuse accusers who have been coached or influenced by unqualified interviewers.
  • Learn how to develop and handle paid, confidential informants.
  • Establish a network of investigative associates in other agencies or police departments.
  • Realize that a criminal profile is merely an investigative guide, not specific evidence of guilt.
  • Learn how guns and ammunition are forensically identified.
  • Know the ways in which a corpse may biologically reveal a general time of death.
  • In death by asphyxia cases, know the signs of strangulation. (Broken hyoid bone; bruises and/or scratches on the neck; and the presence of petechial hemorrhages –pin-point blood spots beneath the skin and in the eyes.)
  • Learn what can be determined from skeletal remains.
  • Learn the language of the autopsy report.
  • Learn how to determine if a fire scene corpse died from the combustion, or was dead before the fire started.
  • Know how to determine if a victim has drowned or was dead before hitting the water.
  • Learn how to recognize homicides made to look like suicides. (Suicides rarely, for example, kill themselves with hatchets, shoot themselves through their clothing, shoot themselves in the abdomen or in the eye, or kill themselves in the presence of another person.)
  • Consider, in crib death cases, the possibility that the baby has been smothered by the mother seeking sympathy and attention. Know the profile of mothers who suffer from the so-called Munchausen by Proxy Syndrome.
  • Know how to locate witnesses and suspects whose whereabouts are unknown.
  • Learn the basic forensic or investigative uses of the computer.
  • In stolen property cases, identify the stolen items by serial number then enter this and other information about the theft into the national data bank called the National Crime Information Center (NCIC).
  • In theft cases involving forced entry (burglaries), conduct a crime scene investigation at the points of entry in search of fingerprints, blood stains, textile evidence, hair follicles, tool marks, paint smears (from burglar tools), footwear impressions and tire tracks.
  • In theft cases with no signs of forced entry, determine who had access to the theft site; look for signs of timely, unexplained affluence among your suspect pool; and be alert to employees, ex-employees, and vendors who have past histories of theft, drug and alcohol problems, gambling debts, domestic problems, or a grudge against the victim company. A good many employee thieves have worked for the company less than six months. If a large amount of cash is missing, the culprit is often a long-time employee with access to the cash and the books.
  • Remember there are three kinds of fences: Business fences who own otherwise legitimate businesses but traffic in stolen goods; broker fences who don’t physically possess stolen property but broker deals between thieves and their customers; and street fences who sell stolen property out of their cars, on the street or at flea markets.
  • Before embarking on a formal surveillance, learn the subject’s daily habits, the people he or she associates with, and the descriptions of vehicles the subject has access to.
  • Learn the basic techniques of surveillance.


  • Ask questions that produce clear, accurate and precise answers. (Could you elaborate? How can I check that out? Could you be more specific?)
  • Get into the habit of conducting follow-up interviews.
  • Listen carefully to what your interviewees are telling you.
  • Take detailed and accurate notes of every interview.
  • Save your notes, they are a part of the investigative file.
  • Conduct phone interviews only if doing it in person is impractical or impossible.
  • Do not make promises to interviewees you cannot keep.
  • In key interviews, prepare the questions in advance.
  • Let interviewees tell their stories without interruption, the questioning stage comes later.


  • Videotape all interrogations conducted at the station, including questioning sessions leading up to the formal interrogation.
  • Resolve contradictions in the confession before getting it signed.
  • Make sure the details in a confession do not contradict what the physical evidence reveals
  • Conduct an interrogation as an one-on-one encounter rather than a session where several detectives are shouting questions at the subject.
  • Prepare carefully for each interrogation, tailoring your approach and technique to the profile and nature of the subject and the crime.
  • Stop the questioning immediately when subject asks for a lawyer.
  • When two subjects are being questioned separately, employ the prisoner dilemma technique. (Telling your subject that his partner is in the other interrogation room pointing his finger at him.)
  • Learn to recognize the body language of deception, keeping in mind that it is not foolproof.
  • When appropriate, exploit the fact you have physical evidence that, by itself, will prove the subject’s guilt. (Give the impression that you do not need a confession.)

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This page was last updated on: Monday, January 7, 2008

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A. James Fisher
Dept. of Political Science & Criminal Justice, 146 Hendricks Hall
Edinboro University of Pennsylvania, Edinboro, PA 16444
e-mail: jfisher@edinboro.edu blog: http://jimfishertruecrime.blogspot.com