Forensics For Dummies. Douglas P. Lyle

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       Reconstructing the crime scene

      After doing an initial walk-through of the crime scene, the investigator begins mentally formulating a hypothesis of the crime, focusing on the likely sequence of events and the locations and positions of everyone present during the crime. Information like the following may be critical in determining the truthfulness of a suspect or the reliability of a witness:

      ✔ Shoeprints may reveal a perpetrator’s every step.

      ✔ Fingerprints may indicate the things the perpetrator touched.

      ✔ Tool marks may signify points of entry or where safes or locked cabinets were pried open.

      ✔ Blood spatters, bullet trajectories, the angle and severity of blows and stabs, and the nature of the victim’s injuries can reveal the actual and relative positions of the assailant, victim, and anyone else who was present during a crime.

      ✔ The physical changes that take place in a corpse (see Chapter 11) may indicate whether the body was moved several hours after death.

      

The investigator looks at each piece of physical evidence to assess whether it supports this theory, considering information obtained not only at the scene but also from the crime lab, medical reports of anyone who was injured, and the medical examiner’s autopsy examination. Anything that doesn’t fit in with or justify the investigator’s theory of the crime must be reconciled; otherwise, the theory must change. As a result, the reconstruction of a crime scene is constantly evolving as more evidence is uncovered.

      The investigator continually tests the developing crime theory against the evidence and avoids making any assumptions, no matter how logical they may seem. An investigator may logically believe that a piece of evidence ended up where it did because of a suspect’s actions, but if the hard evidence doesn’t support this belief, the theory must be held suspect.

      If a gun is found just outside the rear door of a house where a homicide took place, logic suggests that the assailant dropped the gun while escaping. Although that’s certainly a possibility, without solid evidence, ruling out other possibilities may be difficult. For all investigators know, the gun had been tossed there in an attempt to make a domestic homicide look like a murder committed by a burglar whom the victim supposedly caught in the act. Evidence like the spouse’s fingerprints on the gun or the victim’s blood on the spouse’s shoes may, of course, change the theory, but until all evidence in a reconstruction is considered and explained, investigators can’t reach any absolute conclusions.

       Recognizing a staged crime scene

      Staging is when someone who’s committed a crime attempts to make the scene look like something that it isn’t. The most common staging scenario occurs when someone tries to make a murder look like a suicide or an accident. The suspect may move the body or clean certain areas. Say, for example, a husband strikes his wife in the head with a blunt object, killing her. Then he cleans up the bedroom, moves her body into the bathroom, places her in the tub, and calls the paramedics, claiming that she fell while bathing.

      Other common examples of staged crime scenes include the following:

      

Evidence is anything that can be used to determine whether a crime has been committed. Evidence may link a suspect to a scene, corroborate or refute an alibi or statement, identify a perpetrator or victim, exonerate the innocent, induce a confession, or direct further investigation.

      All evidence is not created equal. In fact, evidence is divided into numerous categories depending on its characteristics and reliability. For example, an eyewitness account falls into a different classification than left-behind hair or a piece of clothing.

       Determining whether evidence is direct or circumstantial

      

Evidence can be either direct or circumstantial. Direct evidence establishes a fact. Examples of direct evidence are eyewitness statements and confessions. Circumstantial evidence, on the other hand, requires that a judge and/or jury make an indirect judgment, or inference, about what happened. For example, if a fingerprint or hair found at the crime scene matches that of a suspect, jurors may infer that the print or hair is indeed that of the defendant, and because it was found at the crime scene, links the defendant to the scene.

      Circumstantial evidence is not absolute proof; instead, it provides a general idea of what happened. Most often, evidence identified through forensic science is circumstantial, though direct evidence such as witness and victim statements or suspect confessions may impact the ME’s interpretation of test results or his reconstruction of the crime scene.

      

Circumstantial evidence often is much more reliable than direct evidence. Eyewitnesses are notoriously bad at identifying suspects or recalling events. After all, people tend to interpret what happened instead of simply playing it back like a film loop.

      Furthermore, circumstantial evidence is more objective and is more likely to provide a reliable answer. An eyewitness may be wrong as much as half the time, but fingerprints and DNA evidence can, more often than not, accurately distinguish the individual in question from the other 7 billion people on Earth.