Tag Archives: crime scene

Bugs: the difference between closed case and unsolved murder

eric-benbow

MSU partners with Detroit to investigate death scenes

EAST LANSING, Mich. – As bodies decompose, their types and numbers of bugs and bacteria change. Deciphering the clues they provide could mean the difference between a closed case and an unsolved murder.

Michigan State University is using a more than $866,000 U.S. Department of Justice grant to help Detroit death-scene investigators examine these changing populations. The microbial communities may provide crucial details such as geographical location of death, gender, race, socioeconomic relations and more, said Eric Benbow, MSU entomologist and osteopathic medical specialist.
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Bloodstain Patterns on Textile Surfaces: A Fundamental Analysis

Bloodstains on fabric

Bloodstains on fabric

Article authored by: Stephen Michielsen, Michael Taylor, Namrata Parekh, Feng Ji

Abstract

Bloodstain pattern analysis, BPA, on hard surfaces (such as walls, tables, appliances, hardwood floors, etc.) has grown into a science-based investigative tool that can help determine scenarios that are consistent with or counter to the events described by witnesses or suspects. At the vast majority of crime scenes involving a bloodletting event, textiles are present as apparel, household textiles (sheets, towels), upholstery, carpets, and so forth. Yet, the science of BPA is not able to render the same level of confidence in the analysis as on hard surfaces due to the complex structure of textiles and their ability to wick liquids. In the work described herein, a detailed examination of factors that affect BPA on two textile fabrics, an unbalanced 130 x 70 plain woven 100% cotton bed sheeting fabric (often referred to as a 200 thread count bed sheet) and a 100% cotton jersey knit T-shirt fabric.

During this study, both porcine blood and several synthetic blood recipes were used. The dynamic impact tests (time after impact < 100 ms) used porcine blood, while most wetting and wicking experiments employed synthetic blood (time after impact > 100 ms). Most of the synthetic blood recipes examined performed badly. Either they would not dry or they did not wick into the fabrics, but remained on the surface. A synthetic blood recipe from the American Society for Testing Material (ASTM test method F1819-07) performed well, but its viscosity and surface tension were both lower than typical human blood. Thus, this recipe was modified to lie within the range of surface tension and viscosity of human blood. It was used for the majority of wicking and wetting experiments. In a preliminary comparison, it was found that synthetic blood SB5 behaved similarly to porcine blood in many aspects, but the SB5 stains were significantly larger than the porcine bloodstains. We attributed this difference to the presence of red blood cells, which behave as particles, as well as plasma, which behaves as a liquid, in porcine blood. SB5 is an aqueous solution and behaves entirely as a liquid. Continue reading

Crime Scene Investigation and Fingerprinting

Interesting historic video on crime scene investigation and forensic science. I have a copy as well, that I purchased on DVD from the National Archives. The date on the original is a bit unclear, but it appears to have been made around 1960. It should be noted that some of the practices shown are no longer up to date, and that current safety precautions are not in use. It’s still interesting from a historical standpoint.

Interpretation, Collection and Preservation of Glass Fragments

By Kathy Steck-Flynn

A man is found dead in an abandoned house. Upon examination the medical examiner finds that the man was killed by a single gunshot to the head. Three local teens where observed near the house two days earlier. They are picked up and questioned by police. When pressured, the teens admit to having stolen one of the boys’ father’s guns. They had taken turns shooting at the windows of an abandoned house.

The teens admit that John shot the gun first, then Jay and last was Fred. At the scene the investigators find three bullet holes in a window. They analyze the angle of each bullet hole in relation to the victim and find that the bullet which passed through the far right side of the window pane is the one which fatally wounded the man. Continue reading

An Introduction to Crime Scene Reconstruction for the Criminal Profiler

by Daryl W. Clemens

This article originally appeared in the MAFS newsletter, 27(2), April 1998.

Definitions:

Crime Scene Reconstruction- The use of scientific methods, physical evidence, deductive reasoning and their interrelationships to gain explicit knowledge of the series of events that surround the commission of a crime.
-Association for Crime Scene Reconstruction, The Scene, 4(1), Jan 1997, p. 2.

Criminal Profiling- The application of psychological theory to the analysis and reconstruction of the forensic evidence that relates to an offender’s crime scenes, victims and behaviors.
– Turvey, B., “CP101: An Introduction to Criminal Profiling”, Online Course,
http://www.corpus-delicti.com, May 1997.
Introduction

While both of these activities may appear to be similar and are in fact related, it is important to note that they are not the same. The difference between the two is most easily understood by looking at which questions about the crime they attempt to answer.1,2,3,4 Crime Scene Reconstruction looks at the physical evidence and attempts to determine “What happened?” and “How did it happen?”.5,6 Criminal Profiling looks at the physical evidence and the reconstruction and attempts to determine “Why may this have happened?” and “What does that tell us about Who may have done it?”.7 It is important to keep in mind that only those directly involved in the crime know for sure what happened and why, and they may be unable or unwilling to say. 8,9

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Why Crime Scene Reconstruction Does Not Answer the Why? Question

By Dean H. Garrison, Jr.

This article originally appeared in the MAFS newsletter April 1996.

“I tend not to try to determine why people do things at crime scenes.”
-Criminalist Charles Morton
California v Menedez II, Trial transcript 12-5-95

Crime scene reconstruction may answer the question of where a victim was standing when an axe hit him or who stepped in the pool of blood by the door or what caused the revolver’s hammer to fall or when the third shot hit the car window or how the knife ended up out on the patio, but the crime scene reconstructionist cannot answer the ultimate question, the final question that tugs at everyone’s mind, the all-encompassing, all-seeing, all-knowing question of WHY did the crime happen? This may account for the fact that attorneys (for either side) very seldom ask “Why?” questions. Continue reading

How to Enter a Crime Scene

By Dean H. Garrison, Jr.

This editorial originally appeared in “The Scene”, the newsletter of the Association for Crime Scene Reconstruction.

The yellow tape is up. There are cops everywhere, and maybe even some emergency vehicles. Your Lieutenant or Sergeant or Captain called you on the phone. If they were excited and out-of-breath on the phone, you just know they’re new at this. Somebody’s dead–Oh, my God!–and how soon can you get there? It’s an ungodly hour, of course, and you’re half asleep. Or else it’s early, and all your plans for the rest of the day are shot. And, speaking of shot, there’s a dead guy on the floor somewhere, and he’s shot or stabbed or hit with a lamp or a bottle or a pipe, and he or she is dead or dying or enroute to the emergency room or Dead Right There on the lawn or sprawled out on the bed, or he’s the newest face on the barroom floor. In any case, there’s no need to get overly excited and start flying off in all directions. It’s a homicide, for goodness sake! It’s already too late for somebody. Continue reading