Jay A. Siegel

The use of laser desorption/ionization mass spectrometry in the analysis of inks in questioned documents

Determination of the age of a handwritten or ink printed questioned document can be an important consideration in forensic cases. Most often the age of a document is determined by the chemical behavior of the dyes that make up the ink. Exposure of the dyes to environmental factors such as oxygen and ultraviolet or visible light cause them to degrade. Often this degradation can be correlated to the time since the exposure of the ink to the elements began. A number of methods have been used to track the aging of inks on paper. This paper reports the use of laser desorption mass spectrometry as a valuable tool in not only elucidating the structures of dyes used in inks but tracking the change in their chemistry as they age. This study also explores methods for artificially aging documents using ultraviolet and visible light.

Using STR Analysis to Detect Human DNA from Exploded Pipe Bomb Devices

This study investigated the possibility of recovering a bomb assemblers DNA from an exploded pipe bomb device. Metal and polyvinyl chloride (PVC) pipes were examined to determine if one surface type would allow better DNA recovery than the other. Ten subjects each handled components of one metal and one PVC pipe bomb. The bombs were exploded, the fragments were collected and swabbed using the double swab technique, and the samples were extracted, quantified, amplified, and genotyped using polymerase chain reaction/short tandem repeat (PCR/STR). Of the 20 bombs handled by the subjects, four bombs gave reportable results that matched the subjects known DNA profiles. An additional eight profiles, also matching the subjects known DNA profiles, were generated but were below the reportable threshold. There was no difference in the success rate of obtaining DNA profiles related to the use of either PVC or metal in the manufacture of the pipe bomb. The variables that appeared to have the greatest influence on the success of generating a DNA profile were the amount of fragmentation and subsequent recovery of the bomb fragments. It is suspected that successful DNA profiling could also be dependent upon the bomb assemblers propensity to slough skin cells on objects they handled.

Comparison of gasolines using gas chromatography-mass spectrometry and target ion response

Gas chromatography-mass spectrometry was used to compare gasoline samples obtained from different sources based on the difference in amounts of certain components found in the headspace of gasoline using target response data. Many suspected arson cases involve comparing an ignitable liquid extracted from fire debris to a liquid found in a suspects possession to determine if they could have had a common source. Various component ratios are proposed for determining if an unevaporated gasoline sample could have originated from the same source as an evaporated gasoline extracted from fire debris. Fifty and 75% evaporated gasoline samples were both found to contain similar ratios of certain components when compared with its unevaporated source gasoline. The results of the comparisons in this study demonstrate that for cases involving gasoline that has been evaporated up to 50% and extracted from pine, it is possible to eliminate comparison samples as originating from the same source. The results of the 75% comparisons suggest it may be possible to apply the same type of comparison to cases involving 75% evaporated gasoline.

Time for DNA Disclosure

The legislation that established the U.S. National DNA Index System (NDIS) in 1994 explicitly anticipated that database records would be available for purposes of research and quality control “if personally identifiable information is removed” [42 U.S.C. Sec 14132(b)(3)(D)]. However, the Federal

Legal Aspects of Forensic Science

Forensic science must operate in a legal context. The ultimate result of many scientific analyzes is in a courtroom and the admissibility of this evidence is controlled by rules of evidence. Forensic science is part of the criminal investigation process which starts with the discovery of a crime. It is crucial that crime scene technicians properly recognize, collect, and preserve evidence as it has to be effectively analyzed by forensic scientists. There are Constitutional and other legal constraints on how a criminal investigation can be carried out. These include discovery, search and seizure, protections against self-incrimination, and due process. The production of evidence at a trial is compelled by a subpoena, and order to appear in court. The admissibility of evidence is controlled by a set of rules that govern security of the evidence, authenticity, relevance, and other issues. Scientific evidence is subject to all of these constraints as well as some that apply only to this type of evidence. These constraints arose in part from the decisions in US v. Frye and Daubert v. Merrell-Dow. These cases set out validity and reliability rules for the admission of scientific evidence.

Soil and Glass

Glass and soil can be very important trace evidence in criminal cases. There are many types of glass present in our environment and they are often found at crimes, especially automobile accidents and home and business invasions. Glass is a material somewhat like a solid and a liquid. When glass fragments are large enough to be pieced together like pieces of a jigsaw puzzle, the evidence can be individualized to a particular source. In most cases, the glass fragments are too small to be fracture matched and class characteristics are emphasized. Most commonly, this involves measuring the density and refractive index of the glass fragments. Electron microscopy or ICP-MS can also be used in the analysis of elemental composition of glass.

Fires and Explosions

Fires and explosions are both the result of combustion reactions; where a fuel and oxygen react, sometimes violently and instantaneously to give off large amounts of energy. In fires, the combustion takes place relatively slowly because the fuel and the oxygen are separated, the oxygen being supplied by the air surrounding the fuel. The oxygen is in molecular form and these bonds must be broken before the oxygen can be used. Also, the fuel must be a vapor before it will burn. This also takes time and energy. A fire can be made to simulate an explosion by confining it to a closed space, as is the case with the combustion of gasoline in the cylinders of an internal combustion engine.

Criteria and Concepts for a Model Forensic Science Laboratory

ABSTRACT The National Academy of Sciences Forensic Science Committee issued a report in 2009 that raised a number of issues concerning forensic science. One of the major criticisms of the report concerned the nature of forensic science laboratories in the U.S. The report focused on the fragmentation of the system, the lack of universal accreditation and certification of laboratories and personnel, the management and funding models and a serious lack of standards in reporting, terminology, and methods of analysis. The question thus arises; if one could design the model of a forensic science laboratory, what should it look like? What should its management structure be? Should it be affiliated with a law enforcement agency or independent? Must it be accredited? Must all of the scientists who work in the lab be certified? What standards should be developed that govern the operation of the laboratory? What types of training should be put in place? The answers to these and other, similar questions can provide a framework for the design and implementation of a model forensic science laboratory. In the opinion of the author, such a lab would be independent of law enforcement, accredited and certified, be independently funded by the jurisdiction within which it lies, have standardized, documented training protocols, standardized, validated methods of analysis and a role for research into new methods of analysis. These and other issues are discussed.

Light and Matter

When light strikes a material, it can cause a number of effects, depending upon the nature of the material and the characteristics of the light. Light can be thought of as packets of energy (photons) which can be described in terms of their wavelengths or frequencies. When the energy reaches matter, it can cause effects to the nucleus or the electrons that surround it. This is manifested by the absorption of certain wavelengths of the light. The exact wavelengths of light absorbed are characteristic of the material and the molecules from which it is made. This information helps to characterize materials.

Crime Scene Investigation

The crime scene is the center of the forensic world. The importance of a carefully processed crime scene cannot be overstated. The processing of a crime scene is a one-way street; there is no going back. Standard operating procedures and protocols guide the crime scene investigator, but training, experience, and education all play a role in adapting to each unique crime scene.