The effect on cadaver blood DNA identification by the use of targeted and whole body post-mortem computed tomography angiography.

Post-mortem computed tomography angiography (PMCTA) involves the injection of contrast agents. This could have both a dilution effect on biological fluid samples and could affect subsequent post-contrast analytical laboratory processes. We undertook a small sample study of 10 targeted and 10 whole body PMCTA cases to consider whether or not these two methods of PMCTA could affect post-PMCTA cadaver blood based DNA identification. We used standard methodology to examine DNA from blood samples obtained before and after the PMCTA procedure. We illustrate that neither of these PMCTA methods had an effect on the alleles called following short tandem repeat based DNA profiling, and therefore the ability to undertake post-PMCTA blood based DNA identification.

Anthropological measurement of lower limb and foot bones using multi-detector computed tomography.

Anthropological examination of defleshed bones is the gold standard for osteological measurement in forensic practice. However, multi-detector computed tomography (MDCT) offers the opportunity of three-dimensional imaging of skeletal elements, allowing measurement of bones in any plane without defleshing. We present our experiences of the examination of 15 human lower limbs in different states of decomposition using MDCT. We present our method of imaging and radiological measurement of the bones including sex assessment. The radiological measurements were undertaken by three professional groups--anthropology, radiology, and forensic pathology--both at the site of scanning and at a remote site. The results were compared to anthropological oestological assessment of the defleshed bones. We discuss the limitations of this technique and the potential applications of our observations. We introduce the concept of remote radiological anthropological measurement of bones, so-called tele-anthro-radiology and the role that this could play in providing the facility for standardization of protocols, international peer review and quality assurance schemes.

DNA reviews: DNA identification following CBRN incidents.

Chemical, biological, radioactive, or nuclear (CBRN) incidents can occur due to accident or deliberate action, and may result in substantial loss of life. Whatever the cause, the requirement for identification of the deceased may necessitate the removal of contaminated samples to a DNA laboratory for processing. This review looks at the potential types of CBRN that may result in the requirement for DNA identification of the deceased and investigates the potential risks and difficulties associated with processing samples of this type.

DNA reviews: predicting phenotype.

The prediction of an individuals physical appearance from small biological samples, such as those collected from crime scenes may still sound like science fiction, but how close are we to achieving this goal? This review provides a brief introduction to the areas under investigation for direct and indirect phenotypic inference from DNA alone and suggests some sources of further reading for those interested in gaining a more in-depth knowledge of this complex subject.

Cancer and forensic microsatellites.

Although not directly related, circumstances do occur in forensic investigations whereby cancer studies and forensic science cross paths. This review takes a look at the circumstances under which this may occur, and investigates some potential problems that can arise when tumor tissue is submitted for DNA profile analysis. A background to the underlying molecular biology of tumors is described, highlighting the genetic instabilities that are observed in DNA sequences of similar or identical primary structure to the short tandem repeat markers used in forensic DNA profiling kits.

DNA reviews: low level DNA profiling.

Low copy number (LCN) DNA profiling has recently been scrutinized in the United Kingdom following the comments of Mr Justice Weir made during the trial of suspected terrorist Sean Hoey. Mr Hoey was acquitted of all charges related to the Omagh bombing of 1998, following the inadmissibility of key DNA evidence during this trial. The Association of Chief Police Officers and Crown Prosecution Service, initially suspended the use of this technique, but quickly reinstated its use following an internal enquiry. This review describes the low copy number technique and the sample types that are now routinely collected from suspects, victims, and crime scenes for examination by this method.

Forensic DNA on the internet.

The shear number of websites a vailable addressing the topic of forensic DNA investigation can make the search for specific information time-consuming and frustrating. This review aims to relieve this tension by drawing the reader's attention to a small number of well-produced and maintained websites covering major aspects of the forensic DNA field in genomic and Y chromosome short-tandem repeats and mitochondrial DNA analysis.

How long does it take a static speaking individual to contaminate the immediate environment?

Developments in forensic genetic profiling mean that only a very little DNA is required to generate an identifying profile. However, as this sensitivity increases so does the risk of contamination with non-offender DNA, potentially leading to the conviction of innocents, or release of the guilty. The work of Rutty et al. showed that a static and talking person deposited DNA in front of them within a 15-minute period. This work expands on that of Rutty et al. by determining the time period required for an individual to deposit sufficient DNA for a positive identification to be made, and the distance that this contamination can be detected from the speaking individual. To simulate a scene of crime, sheets of Benchkote(®) were used to represent an area of interest and an unprotected subject talked over them for a variety of times, in a variety of positions (standing, kneeling, and sitting at a desk). Results show that contamination by talking in both kneeling and sitting positions occurred almost immediately (<30 seconds, but not from just one sentence) up to 69 cm from the subject. When standing, contamination could be observed up to a maximum 115 cm from the subject, and was only present in one of three repeats when talking for only 30 seconds. This article illustrates how rapidly a static person can potentially contaminate an area in front of him or herself within a laboratory or scene environment, just by talking.

Disaster victim identification.

In the event of any mass fatality incident, despite the cause, disaster victim identification must be undertaken; the humanitarian and legal responsibility for this falls on the forensic community. Mass fatality incidents can be natural (e.g., tsunamis, earthquakes, hurricanes), accidental (e.g., building collapse, ship sinking) or can occur as a result of a terrorist attack. Terrorism alone has been responsible for thousands of deaths in recent years and can be encountered in many forms (e.g., suicide bombings, airplane hijackings). In mass fatality situations, the experitise of many specialities are called on to assist in the identification efforts and to allow for the speedy return of recovered human remains to the relatives of the deceased. Today, DNA plays a vital but never solitary role in disaster victim identification.

Sex determination.

Determing the sex of a give DNA sample can provide criminal investigators with useful intelligence and can aid the identification of missing persons and disaster victims. Polymerase chain reaction-based systems that amplify regions of the am elogenin gene have become the method of choice for sex determination of biological samples. This system can, however, result in false female sex designation when mutations affect primer binding sites of the Y homolog of this target sequence, causing drop out of the Y amplification product. Erroneous sex determination could have drastic consequences when applied to forensic situations by misdirecting investigators or hindering the identification of deceased individuals. Current methods of sex determination are described and possible alternative approaches to avoid errors are discussed.

Automated DNA profile analysis.

DNA profile analysis is not a simple process. Stringent demands are placed on the accuracy and consistency of forensic evidence so that complex, robust, and reproducible guidelines are necessary to assist the analyst and ensure mistakes are eliminated before a final profile is reported. The guidelines used for forensic DNA profile interpretation are formulated by investigation and statistical evaluation of all aspects of the analytical procedure. All the resulting rules, formulas, and thresholds are perfectly suited to programming of "expert systems"-software programs that imitate the human expert in decision-based processes to formulate a conclusion. Expert systems in forensic DNA analysis will contribute greatly to this field by increasing analytical throughput. The net result of this will be an increase in the human resources available for the research and development of improved methodologies, to ensure that forensic DNA profiling continues to advance at its current impressive rate.

Mini-STRs.

The use of the short-tandem repeat (STR) as the DNA marker of choice in forensic profiling has lead to the construction of criminal intelligence databases that now contain millions of profiles used in the detection and linking of suspects and scenes. The incredible size and success rate of current systems have ensured that efforts to move away from STR profiling and toward the use of alternate DNA markers are practically impossible, mainly because of the financial implications involved in such a move. Problems are routinely encountered when template DNA is of suboptimal condition, as is commonly the case in the forensic laboratory, whereby full profile generation of degraded samples is not possible. A redesigned amplification protocol that results in the generation of shorter polymerase chain reaction products yet is fully compatible with current STR databases has been introduced: the MiniPlex.

Nonhuman DNA.

DNA has now been used to aid criminal investigation for more than 20 years. The vast majority of this evidence has been produced by profiling of human genetic material. However, DNA profiling technology is not restricted to the human genome. Regions of genetic material displaying similar characteristics to markers used for forensic purposes in the human genome have been identified in many other animal species. Although nonhuman DNA profiling has been used for a small number of forensic investigations, the full potential of this evidence type has yet to be realized.

Lab-on-a-chip technology.

The techniques and laboratory processes involved in the production of DNA profiles for forensic applications are well developed, robust, and reliable. Unfortunately, they can now also be considered too slow and expensive to be able to match the ever-increasing demands placed upon them. The most rapid DNA profiling instrumentation in current usage are capillary electrophoresis (CE) systems. CE systems have greatly enhanced visualization and analysis throughput, but are still unable to keep up with current demand. However, developments in nanobiotechnology are allowing for the production of miniature systems to decrease the time and costs involved in profile production.