Chemistry: Applications in Espionage, Intelligence, and Security Issues

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Chemistry: Applications in Espionage, Intelligence, and Security Issues

█ JUDYTH SASSOON

From the detection of forgeries to the identification of criminal suspects, the techniques of chemistry have many applications in areas relating to espionage, intelligence and security. Analytical chemistry, the branch of chemistry concerned with the analysis of substances, is of particular importance. The study of the chemical composition of a compound gives a qualitative analysis, while the determination if its concentration involves quantitative analysis. Chemists utilize a range of different skills to help security services in areas as wide-ranging as drugs, firearms, toxicology, and fiber analysis. For example forensic chemistry concerns the detection and characterization of substances at crime scenes. These might include bomb fragment analysis, fire investigations, firearms discharge analysis, poison or toxin analysis and various other types of chemical residue analysis. In these instances, sophisticated analytical techniques are used to identify minute residues of paint, fire accelerants, human hair, body fluids or tissues. Advanced spectroscopic and separation procedures can often clarify confusing circumstantial evidence.

Modern analytical chemical laboratories can use both classical "wet" methods (gravimetric or volumetric procedures) employing chemical reactions to perform the analysis, or instrumentation, which makes critical measurements during an analysis. A number of separation methods are useful either prior to chemical analysis or as direct methods in the analysis. These methods include distillation, selective precipitation, filtration, osmosis, and extraction. Most analytical procedures in the forensic laboratory now use some instrumentation and many are fully automated. The instrument-based methods of analysis are divided into categories according to the type of process used to perform the analysis. Optical instruments such

as spectroscopes comprise the first major group and measure electromagnetic radiation, which is either absorbed (absorption spectroscopy) or emitted (emission spectroscopy) by a sample. The wavelength at which this occurs can be used for qualitative analysis, while the amount of radiation can be useful for quantification. Spectroscopy involves the use of radio, infrared, ultraviolet, visible and x-ray regions of the electromagnetic spectrum.

Of the instrumental separation methods, chromatography and its variations are the most widely used. Chromatography is a technique whereby a mixture is separated into its components by the reactive adherence of each component to a stationary phase while a mobile phase passes over the stationary phase. Chromatography is divided into categories, depending on the physical state of the stationary and mobile phases. Examples include gas-solid, gas-liquid, liquid-liquid or liquid-solid chromatography and also thin layer, paper, and gel permeation chromatography. The applications of these techniques in forensics can provide much intelligence information in the form of physical evidence that can be used subsequently by security forces.

The techniques above are frequently employed in the analysis of substances from sites of criminal or terrorist activity. For example, the examination of debris at the scene of a fire can provide data to show if the fire started accidentally or deliberately. The correct identification of the source and the presence of accelerants can link the fire to an arson suspect. Similarly, detailed laboratory analysis of debris and trace evidence from explosion scenes (domestic, commercial, suspected criminal, or terrorist) as well as a detailed chemical knowledge of the capacity of materials to form explosions can yield information showing the nature of the source. If a firearm is discharged, gunshot residue such as burnt or partly burnt gunpowder and components from the primer compound (e.g. lead, barium, and antimony are also thrown out into the surroundings). Firearms discharge residues that may be deposited on any object near to a gun when it is fired, or on any object that subsequently touches the gun. When an object is shot at a relatively close range, gunshot residues are deposited, and sometimes violently impacted, onto the target. The nature and distribution of these residues can match a target to a weapon and can also be used to determine the distance from the gun's muzzle from point of impact.

Chemical analysis becomes important in the study of glass and building materials from the site of an incident. Glass is frequently broken when a criminal offence takes place and building materials such as plaster, mortar, bricks, slate or loft insulation may be dislodged if illegal entry is gained into a building. Fragments of either can adhere to clothing and may be recovered from a suspect. A comparison of these with similar materials at the incident scene can link a suspect to a crime. Similarly, paint can be conveyed between surfaces following contact, and analysis of paint composition and layering can be used to connect paint fragments to a crime. The most common occurrence is the transfer of paint between vehicles or objects in road traffic accidents. Paint fragments can also adhere to items of clothing following contact with loose flakes on surfaces such as windows at the scene of burglaries. Paint analysis can also be applicable in circumstances where painted car parts are suspected of having been exchanged between vehicles.

Chemical analysis of cloth fibers, stains and organic materials such as human hair and body fluids provide vital evidence in, for example, homicide cases. In the past, biochemical blood typing using antisera and the matching of hair types could not provide absolute identification of a suspect or victim, although it could narrow the possibilities down. Today, however, even minute quantities of blood, semen, skin cells and hair can yield DNA profiles. DNA from different individuals differs in base sequence and, theoretically every individual with the exception of identical twins, can be identified solely on the basis of their DNA sequences. However, a complete DNA analysis of individuals is a daunting and time consuming task because of the many millions of bases in the human genome. The possibilities for routine genome analysis do not exist at present. Instead, DNA matching is performed by analysing shorter, highly polymorphic single locus genes such as the VNTR genes. This method can establish a "DNA signature" for almost any individual. Biochemical analysis of these sequences can determine whether two DNA samples are from the same person, related people, or unrelated people. Though these methods also do not yield absolute certainties, they are nevertheless more precise than traditional methods such as blood typing.

DNA profiling as a crime intelligence aid involves the use of basic chemical and biochemical procedures. DNA is chemically isolated from the cell or tissue sample, amplified using the enzymes in the polymerase chain reaction (PCR), and then analyzed by electrophoretic methods. The DNA profile from the scene of the crime can be compared with a DNA profile from a suspect and a match can link the suspect to the crime. If there is no suspect, the DNA profile can be matched with profiles stored on to the National DNA Database (NDNAD). If there is no match with the NDNAD, it is sometimes decided to carry out an intelligence-led screen (a mass DNA screen). A target group of individuals, for example, men within a certain age range living in a town or area, are asked to voluntarily provide DNA samples, which are then analyzed and compared with a profile linked to a particular crime. Samples from volunteers are not stored on the NDNAD, and are destroyed if they do not match the crime profile.

Thus, the sensitivity and accuracy of chemical analytical methods lie at the heart of forensic science and, with the advances in biochemical techniques, provide essential tools for crime intelligence investigations.