Bloodstain Pattern Evidence

Objective Approaches and Case Applications

Anita Y. Wonder

• Editore: Academic Press
• Anno: 2011
• ISBN:
  9780080549712
• Argomento: Social Sciences
• Categoria: Criminology

In Bloodstain Pattern Evidence, the concepts introduced in the author's first book, Blood Dynamics, are updated and applied to provide essential answers in the resolution of actual crimes. The book is accessible to all levels of investigators, regardless of academic background, and allows readers to develop a fundamental understanding of the underlying scientific principles behind bloodstain pattern evidence.

Bloodstain Pattern Evidence builds on the fundamental ideas brought about by an understanding of Non-Newtonian dynamics, and illustrates through case work the practical forensic science applications of these principles to the analysis of bloodstain patterns.

• Extensive case examples provide practical application of essential pattern analysis principles
• Extensively illustrated with over 350 photos and line drawings
• Takes a unique and scientific approach to bloodstain pattern analysis by exploring the fundamentals of fluid behavior

SECTION II: CASE APPLICATIONS

The following cases were processed from photographs, occasional visits to the scenes (seldom fresh), and usually confirmed with autopsy, medical, and interview reports. The cases were selected solely for the purpose of academic review and the hope that my experiences will benefit future applications of bloodstain pattern evidence (BPE). It is the nature of forensic science that differences of opinion and interpretation will always exist. Two quotes come to mind with regard to an anticipation of criticism.

If you come across error, rather than uprooting it or knocking it down, see if you can trim it patiently, allowing the light to shine upon the nucleus of goodness and truth that usually is not missing even in erroneous opinions. Pope John Paul I (1912–1978)¹

Nothing would be done at all if one waited until one could do it so well that no one could find fault with it. John Henry Newman (1801–1890)²

With the second quote it is accepted that others may provide different and perhaps even better conclusions. Such is the source of knowledge and the advancement of science.

Figure 5-1 Chicken House IV, by American Painter Eva Martino, 2004.

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¹Found in In God’s Name, by David Yallop. (1984). Bantam, 20.

²Found online in The Ultimate Success Quotations Library. (1997).

CHAPTER 5

TIMING IS EVERYTHING

Publisher Summary

This chapter provides a case study, where a lady was killed in a car accident. A suspicious death was originally treated as a traffic accident investigation (TAI). There are three types of sources for blood at the scenes of violent crime: injuries, volume blood (pools), and prior wet stains. Prior wet stains can be any bloodstains that remain wet for sufficient time to provide a blood source for subsequent staining. Usually, these are limited to large drips, blood flows, or very bloody transfers. During the time required to dry, transfer (contact, compression stains) or drip castoffs (LVIS, drip trails, passive, gravitational stains) may occur. Bloodspatters generally dry too rapidly to provide a good blood source unless someone steps into or rubs the array immediately following drop distribution. The predominance of other possible blood sources involves flows and transfers. Numerous other case studies are discussed in the chapter.

INTRODUCTION

Although the usual procedure is to look at the scene first, or photographs of it, the format for these cases begin with the identification of blood sources available. In practice, medical records and autopsy reports are not available until after bloodstain patterns have been classified into major categories and the preliminary events sequenced. In the academic use of material, however, it is convenient to know what blood sources were available. All cases should be approached after becoming familiar with the investigative tools in the appendixes.

There are many good procedure resources for approaching crime scenes in general. This work is to provide additional information regarding one form of evidence rather than restate what other well-qualified authors have covered. Each case is presented in a format that should make it unimportant whether the case was analyzed from the defense or the prosecution viewpoint. In fact, casework for both sides of the aisle has been processed by the author. Two cases were reviewed from one perspective and later reviewed for the opposing council. Mistakes were made at all levels—including by the author—but brilliant sleuthing also was found at all levels. It is the nature of humans, however, that we learn best from our mistakes and not from patting ourselves on the back. Nothing in this book is directed at the discomfort of any individuals encountered during my 30 years’ experience with the amalgam called the Criminal Justice System.

FURTHER DISCUSSION OF VELOCITY IMPACT SPATTER TERMINOLOGY-SUBJECTIVITY

After Dr. Kirk’s death from cancer in 1970, changes to the original semantics occurred. Instead of the impact and relative velocity being considered at the target surface, the meaning was shifted to the contact point between a weapon and a blood source/injury. This has caused confusion in part because the original concept of contact between a single blood drop and a target also was retained. So impact site became both Dr. Kirk’s definition as the site where an individual stain was recorded on a surface, as well as the new definition of the area where a weapon opened a blood source to distribute drops.

Pretests, submitted to classes of students with little background up to completion of two or more 40-hour Bloodstain Pattern workshops, show that the velocity impact spatter (VIS) terms often are regarded in a subjective context. Although this has been corrected in most training formats, many participants still feel that VIS means a specific size of bloodstain identifies specific events, i.e., gunshot is identified by a specific size spatter (less than 1 millimeter in diameter) called high velocity impact spatter (HVIS). Beating bloodspatters are identified by specific size (1–4 mm) bloodstains called medium velocity impact spatter (MVIS). Impact events, however, involve a variety of drop sizes within each degree of force, and in fact are characterized by the presence of an array of sizes, never limited to a single one nor narrow range of sizes. Different pattern dynamics, impact, cast offs, and arterial damage, also distribute drop arrays with considerable overlap in stain size ranges.³ There is no such thing as one identifying bloodstain size, nor narrow limit range, for an entire dynamic category. Patterns consisting of many spots of blood can result from different acts or events, not all are criminal.

Cast offs: Blood drops which separate from the surface of a carrier.

The main problem with using VIS terms as originating at an injury rather than as Dr. Kirk’s approach of a blood drop at contact with a surface, is that we are no longer dealing with identifying individual bloodstains at a single location in time and space. By current methodology labeling is based on the collection of stains on a surface separated from the defining velocity event. This is a shift in application of the term in an analysis, from a single item of physical evidence at one point in time and space to the behavior of a group of spots between a highly variable event (not an item of evidence) and recording upon a distant surface with its own set of variable conditions as well as conditions between the two. To perform this analysis, the analyst must first assume a link between the two locations, contact with a blood source and recorded spatter pattern. Experience has shown that the recorded spatter grouping is not always from the assumed dynamic event. Shifting from a velocity component at the contact between target and blood drop to the contact of a weapon at a blood source, then reading the result...