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Bidis are small handmade cigarettes consisting of ~0.2 g of tobacco flakes rolled in a dried leaf of 'Tendu' (Diospyros melanoxylon) or Piliostigma racemosum and tied with a thin thread. They have gained worldwide popularity among smokers and are often collected as forensic DNA evidence from crime scenes and processed similarly to cigarette butts. However, bidi's composition and manufacturing process differs distinctly from the cigarette, and hence the optimal processing for DNA analysis should not be assumed to be similar to cigarette butts. In the present study, the methodical evaluation of the bidi for DNA analysis is reported and an additional process of cell elution from bidi stubs prior to DNA extraction is systematically compared with the direct lysis of bidi stubs which is identical to the standard practice in forensic labs for cigarette butts. In terms of cell recovery from bidi stubs, the SDS based Cell Elution Buffer (CEB) proved to be better than Tween20 based CEB. The three components (cell-elute, supernatant, and processed stub) obtained after the cell elution process of smoked bidi stubs showed varying amounts of DNA. The cell-elute and processed stub exhibited high quality DNA, resulting in 90-100% of the samples giving a full STR profile. On the contrary, the directly lysed stubs yielded high quantity but low quality of DNA, resulting in only 40% of the samples with full STR profiles. The cell elution process enables three components namely cell-elute, supernatant and processed stub from the same bidi to be used for forensic DNA analysis, although the cell-elute proved to be the best source of DNA for STR profiling. The current study demonstrates that the additional cell elution process proved to be an essential step prior to DNA extraction procedure for bidi stubs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Blood at crime scenes is one of the most significant traces of evidence in investigation proceedings. Cleaning up these traces with household cleaning products, often containing bleaching agents, inhibits or complicates the detection of DNA. In this study, human blood was applied onto different floor coverings (carpet, laminate, parquet, PVC, tile) and subsequently cleaned with water and bleaching agents (hydrogen peroxide, sodium hypochlorite, DanKlorix®, Vanish Oxi Action®) at different times. Samples have been collected afterwards from the floors. The samples underwent a quantitative and qualitative DNA analysis. Cleaning smooth surfaces with water is usually sufficed to prohibit retrieving a DNA profile in most of the cases. Cleaning carpets was more difficult due to their absorbent surface whereas the use of bleaching agents caused an additional reduction of verifiable DNA concentrations. Retrieving partial or complete profiles after the use of bleaching agents was only possible when cleaning with low concentrations of 3% hydrogen peroxide.

The recovery of fingermarks and DNA from the same location at a crime scene can be problematic because of contamination issues associated with powdering or laboratory-based visualisation processes and/or the perceived destructive impact of commonly employed 'swabbing' approaches to DNA recovery. Previous research in a controlled environment demonstrated that it was possible to recover DNA and latent fingermarks from the same location on various substrates when an adhesive approach to DNA recovery was used. The aim of this research was to conduct a pseudo-operational trial into the dual recovery of DNA and fingermarks using gel lifters for DNA recovery. Participants were asked to voluntarily and anonymously donate a wide variety of porous and non-porous substrates post handling. No instruction as to fingermark deposition nor environmental storage was provided. BVDA gel lifters were applied to the substrates to replicate DNA recovery followed by the application of fingermark visualisation processes. The number and quality of the fingermarks was established using a grading approach. Application factors were also investigated to consider the effects of user variation. The results demonstrated that it was possible to recover DNA and fingermarks considered to be capable of supporting an identification. Fingermark quality post lifting was dependant on the substrates used. The weight applied to the gel during its application was a lesser contributing factor than the duration of its contact with the surface. There was a greater chance of leaving the fingermarks unaltered with the application of a low weight and instantaneous retraction., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Body fluid identification in crime scene investigations aids in reconstruction of crime scenes. Several studies have identified and reported differentially methylated sites (DMSs) and regions (DMRs) which differ between forensically relevant tissues (tDMRs) and body fluids. Diverse factors affect methylation patterns such as the environment, diets, lifestyle, disease, ethnicity, genetic variation, amongst others. Thus, it is important to analyse the stability of markers employed for forensic identification. Furthermore, even though epigenetic modifications are described as stable and heritable, epigenetic inheritance of potential markers for body fluid identification needs to be assessed in the long term. Here, we discuss the current status of reported DNA methylation-based markers and their verification studies. Such thorough investigation is crucial to develop a stable panel of DNA methylation-based markers for accurate body fluid identification.

Body fluid analysis has played a crucial role in ascertaining various characteristics and has greatly aided in reconstructing events during crime scene investigation. It is often presumed that crimes that involve violence and mental disturbances such as murder or sexual assault provide good sources of body fluids such as blood, saliva, semen, vaginal secretions, urine and tears. Tears are secreted in response to any emotional or stressful situations and may be found deposited on surfaces such as bedding, tissue paper or cloth. In the absence of the commonly noted body fluids such as blood or saliva, tears can play an important role that can lead to personal identification by examining the biochemistry and molecular aspects to obtain a full DNA profile. Additionally, identification of an individual may be done by carefully observing certain unique eye characteristics such as heterochromia which is highly individualistic. Characteristics of eyewear such as spectacles and contact lenses have unique properties and prescription criteria for correcting an individual's eyesight that can provide vital clues in understanding the visual ability of an individual. In crime scene investigation, the presence or absence of eyewear provides immense evidentiary value that has greatly aided in solving cases such as Janet Abaroa's Murder. This paper provides a systematic review of the possibility of using tears and eyewear for the purpose of forensic investigation and to statistically support the inferences with prescription databases which may be initiated across different populations. Forensic Optometry is yet to get streamlined along with the routinely followed investigative techniques and scientifically explored although no standard protocols exist to analyse eyewear. The use of behavioural optometry is gaining attention in the context of driving laws of different countries and is a simple but powerful indicator of abnormal behaviour. It is speculated that the last seen image referred to as an 'Optogram' of an individual may be captured in the retina since our eyes functions like a camera. Although this claim is considerably unexplored, it is quite possible that the last seen image of a criminal, objects or a place may be noted that can positively help in linking individuals at the scene of crime or identify the primary crime location. In this review, the potential for new insights into the analysis of tears, eye and eyewear characteristics have been explored., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Quantitative genomic and proteomic evaluation of human latent fingerprint depositions represents a challenge within the forensic field, due to the high variability in the amount of DNA and protein initially deposited. To better assess recovery techniques for touch depositions, we present a method to produce simple and customizable artificial fingerprints. These artificial fingerprint samples include the primary components of a typical latent fingerprint, specifically sebaceous fluid, eccrine perspiration, extracellular DNA, and proteinaceous epidermal skin material (i.e., shed skin cells). A commercially available emulsion of sebaceous and eccrine perspiration material provides a chemically-relevant suspension solution for fingerprint deposition, simplifying artificial fingerprint production. Extracted human genomic DNA is added to accurately mimic the extracellular DNA content of a typical latent print and comparable DNA yields are recovered from the artificial prints relative to human prints across surface types. Capitalizing on recent advancements in the use of protein sequence identification for human forensic analysis, these samples also contain a representative quantity of protein, originating from epidermal skin cells collected from the fingers and palms of volunteers. Proteomic sequencing by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis indicates a high level of protein overlap between artificial and latent prints. Data are available via ProteomeXchange with identifier PXD015445. By including known quantities of DNA and protein into each artificial print, this method enables total DNA and protein recovery to be quantitatively assessed across different sample collection and extraction methods to better evaluate extraction efficiency. Collectively, these artificial fingerprint samples are simple to make, highly versatile and customizable, and accurately represent the biochemical composition and biological signatures of human fingerprints., Competing Interests: The authors DSL, KQS, TEM, ARS, MLP, NCA, BCL, KLW, MWG, and FCH are employed by Signature Science, LLC. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The authors declare no other relevant affiliations or financial involvement with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Biological evidence analysis from contact traces is adversely affected by low quantity and quality of DNA. Proteins in these samples contain potentially individualizing information and may be particularly important for difficult surfaces such as brass, where DNA may yield incomplete profiles. In this study, touched unfired brass cartridges were sampled using dry tape or wet swabs and analyzed by separating DNA and protein from the same collected material, thus producing both genomic and proteomic information. DNA recovery was similar for both collection methods, with tape yielding an average of 1.36 ± 1.87 ng and swabs, 1.34 ± 3.04 ng. Analysis by mass spectrometry identified 95 proteins, with the two collection methods showing no significant difference (p = 0.76) in the average number of collected proteins: 44.5 ± 10.9, (tape) versus 47.9 ± 20.4 (swabs). Proteins can be collected from fingerprints at levels necessary to provide identifying information, thus expanding information obtained from challenging evidence., (© 2019 American Academy of Forensic Sciences.)

Sexual assault evidence samples require the use of a specific process known as a differential digestion to separate sperm from nonsperm cells prior to DNA extraction. An automated differential digestion process was developed using a selective degradation technique, which uses DNase I to digest the remaining nonsperm DNA in the sperm fraction. The use of DNase on pristine samples, as well as aged and degraded samples, was assessed to ensure that the quantity and quality of the sperm DNA were not compromised or adversely affected. Samples processed using the selective degradation technique yielded comparable DNA yield and DNA typing data to the conventional differential digestion process. The automated process utilized 96-well plates for high throughput and incorporated microscope slide preparations for confirmation of sperm. It reduced processing time by about sixfold and was paramount in the elimination of the Oakland Police Department Criminalistics Laboratory's sexual assault kit backlog., (© 2018 American Academy of Forensic Sciences.)

We display a nucleic acid controlled AgNC platform for latent fingerprint visualization. The versatile emission of aptamer-modified AgNCs was regulated by the nearby DNA regions. Multi-color images for simultaneous visualization of fingerprints and exogenous components were successfully obtained. A quantitative detection strategy for exogenous substances in fingerprints was also established.

Background: The greater sage-grouse (Centrocercus urophasianus) is a ground-nesting bird from the Northern Rocky Mountains and a species at risk of extinction in in multiple U.S. states and Canada. Herein we report results from a proof of concept that mitochondrial and nuclear DNAs from mammalian predator saliva could be non-invasively collected from depredated greater sage-grouse eggshells and carcasses and used for predator species identification. Molecular forensic approaches have been applied to identify predators from depredated remains as one strategy to better understand predator-prey dynamics and guide management strategies. This can aid conservation efforts by correctly identifying predators most likely to impact threatened and endangered species. DNA isolated from non-invasive samples around nesting sites (e.g. fecal or hair samples) is one method that can increase the success and accuracy of predator species identification when compared to relying on nest remains alone., Results: Predator saliva DNA was collected from depredated eggshells and carcasses using swabs. We sequenced two partial fragments of two mitochondrial genes and obtained microsatellite genotypes using canid specific primers for species and individual identification, respectively. Using this multilocus approach we were able to identify predators, at least down to family, from 11 out of 14 nests (79%) and three out of seven carcasses (47%). Predators detected most frequently were canids (86%), while other taxa included rodents, a striped skunk, and cattle. We attempted to match the genotypes of individual coyotes obtained from eggshells and carcasses with those obtained from fecal samples and coyotes collected in the areas, but no genotype matches were found., Conclusion: Predation is a main cause of nest failure in ground-nesting birds and can impact reproduction and recruitment. To inform predator management for ground-nesting bird conservation, accurate identification of predator species is necessary. Considering predation can have a high impact on recruitment, predation events are very difficult to observe, and predator species are difficult to identify visually from nest remains, molecular approaches that reduce the need to observe or handle animals offer an additional tool to better understand predator-prey dynamics at nesting sites.

With the introduction of new multiplex PCR kits and instrumentation such as the Applied Biosystems 3500xl, there has recently been a rapid change in technology that has greatly increased sensitivity of detection so that a DNA profile can routinely be obtained from only a few cells. Research to evaluate the risks of passive transfer has not kept pace with this development; hence the risk of innocent DNA transfer at the crime-scene is currently not properly understood. The purpose of this study was to investigate the possibility of investigator-mediated transfer of DNA traces with disposable nitrile-gloves used during crime-scene examinations. We investigated the primary transfer of freshly deposited DNA from touched plastic, wood or metal substrates and secondary and tertiary transfer by a person wearing disposable nitrile-gloves and onto a third object. We show that with use of the new highly sensitive technologies available in forensic DNA analysis there is an enhanced probability to obtain a DNA-profile which has not been directly deposited on the object but is an outcome of one or more transfer events. The nitrile-gloves used by investigators during exhibit examination can act as a vector for DNA transfer from one item to another. We have shown that the amount of DNA deposited on an object affects the probability of transfer. Secondly, the type of substrate material that DNA is deposited onto has an impact on transfer rates., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Gun crimes are a significant problem facing law enforcement agencies. Traditional forensic examination of firearms involves comparisons of markings imparted to bullets and cartridge casings during the firing process. DNA testing of casings and cartridges may not be routinely done in crime laboratories due a variety of factors including the typically low amounts of DNA recovered. The San Diego Police Department (SDPD) Crime Laboratory conducted a study to optimize the collection and profiling of DNA from fired and unfired ammunition. The method was optimized to where interpretable DNA results were obtained for 26.1% of the total number of forensic casework evidence samples, and provided some insights into the level of secondary transfer that might be expected from this type of evidence. Briefly detailed are the results from the experimental study and the forensic casework analysis using the optimized process. Mixtures (samples having more DNA types than the loader's known genotype detected or visible at any marker) were obtained in 39.8% of research samples and the likely source of DNA mixtures is discussed., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

The polymerase chain reaction (PCR) is a popular method to copy DNA in vitro. Its invention revolutionized fields ranging from clinical medicine to anthropology, molecular biology, and forensic biology. The method employs one of many available heat-stable DNA polymerases in a reaction that is repeated many times in situ. The DNA polymerase reads a template DNA strand and using the components of the reaction mix, catalyzes the addition of free 2'-deoxynucleotide triphosphate nitrogenous bases to short segment of DNA that forms a complement with the template via Watson-Crick base pairing. This short segment of DNA is referred to as a PCR primer and it is essential to the success of the reaction. The most widely used application of PCR in forensic labs is the amplification of short tandem repeat (STR) loci used in DNA typing. The STRs are routinely evaluated in concert with 16 or more reactions, a multiplex, run in one test tube simultaneously. In a multiplex, it is essential that the primers work specifically and accurately on the intended reactions without hindering the other reactions. The primers, which are very specific, also can be used to probe single nucleotide polymorphisms (SNPs) in a DNA sequence of interest by single base extension. Primers are often designed using one of many available automated software packages. Here the process of manually designing PCR primers for forensic biology using no-cost software is described.

Soil is commonly used in forensic casework to provide discriminatory power to link a suspect to a crime scene. Standard analyses examine the intrinsic properties of soils, including mineralogy, geophysics, texture and colour; however, soils can also support a vast amount of organisms, which can be examined using DNA fingerprinting techniques. Many previous genetic analyses have relied on patterns of fragment length variation produced by amplification of unidentified taxa in the soil extract. In contrast, the development of advanced DNA sequencing technologies now provides the ability to generate a detailed picture of soil microbial communities and the taxa present, allowing for improved discrimination between samples. However, DNA must be efficiently extracted from the complex soil matrix to achieve accurate and reproducible DNA sequencing results, and extraction efficacy is highly dependent on the soil type and method used. As a result, a consideration of soil properties is important when estimating the likelihood of successful DNA extraction. This would include a basic understanding of soil components, their interactions with DNA molecules and the factors that affect such interactions. This review highlights some important considerations required prior to DNA extraction and discusses the use of common chemical reagents in soil DNA extraction protocols to achieve maximum efficacy. Together, the information presented here is designed to facilitate informed decisions about the most appropriate sampling and extraction methodology, relevant both to the soil type and the details of a specific forensic case, to ensure sufficient DNA yield and enable successful analysis., (Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.)

Biological samples are vulnerable to degradation from the time they are collected until they are analysed at the laboratory. Biological contaminants, such as bacteria, fungi, and enzymes, as well as environmental factors, such as sunlight, heat, and humidity, can increase the rate of DNA degradation. Currently, DNA samples are normally dried or frozen to limit their degradation prior to their arrival at the laboratory. In this study, the effect of the sample drying rate on DNA preservation was investigated, as well as a comparison between drying and freezing methods. The drying performances of two commercially available DNA collection tools (swab and drying tube) with different drying rates were evaluated. The swabs were used to collect human saliva, placed into the drying tubes, and stored in a controlled environment at 25°C and 60% relative humidity, or frozen at -20°C, for 2 weeks. Swabs that were stored in fast sample drying tubes yielded 95% recoverable DNA, whereas swabs stored in tubes with slower sample drying rates yielded only 12% recoverable DNA; saliva stored in a microtube at -20°C was used as a control. Thus, DNA sampling tools that offer rapid drying can significantly improve the preservation of DNA collected on a swab, increasing the quantity of DNA available for subsequent analysis.

The development of non-manipulative molecular tools to determine the origin of parasite infections in the animal trade (if infected before their export or import) is of great interest worldwide for both the animal trade industry and for animal welfare. Molecular tools have a wide range of applications, including forensic identification, wildlife preservation and conservation, veterinary public health protection, and food safety. Nonetheless, genetic markers were not reported to detect the source of infection in the animal trade. In this study we tested the applicability of molecular tools to detect the origin of Sarcoptes mite infection of wildebeest imported by the United Arab Emirate (UAE) from Tanzania. Using one multiplex of seven microsatellite markers and control samples from UAE, Kenya and Italy, we demonstrated the usefulness of the multiplex STR-typing as a molecular tool of pivotal interest to help commercialist, authorities, and conservationists, to identify the geographical origin of parasitic infections.

Heparin traditionally used as an anticoagulant for blood preparations is one of the most powerful inhibitors of the polymerase chain reaction. The molecular genetic analysis for the purpose of forensic medical expertise encounters difficulties when DNA preparations obtained from heparinized samples have to be used. In our practical work, we were faced with the necessity to use heparin-treated blood samples. It turned out impossible to eliminated heparin from DNA isolated from these samples by the known methods. In order to obviate this difficulty, we have developed a special method for obtaining DNA from heparinized blood preparations suitable for the purpose of forensic medical expertise. The new technique includes the stages of preliminary extraction and purification of the blood cell fraction.

The polymorphism of short tandem repeats (STRs) is commonly used for human identity testing. Many commercial kits are available for this purpose, in which multiplex PCR for 10-16 STRs is usually used. For optimal results, the kits recommend rather limited conditions, which not all forensic samples can satisfy. We increased the efficiency of several commercial kits by modifying the components and reaction parameters (primer concentration and cycle number, and annealing and extension time). To simulate low copy number, we used 1:10 and 1:100 diluted samples compared to the recommended concentration. A change in cycle number, annealing and extension time, and primer concentration showed various results. Fine-tuning of PCR conditions by combining the described changes, decreasing the primer concentration, and increasing the annealing and extension time together with increasing the cycling number dramatically increased the efficiency of the reaction, even in low-copy-number simulated samples. Detailed information for several kit components or kits with different components targeting difficult sample conditions, including low copy number, would be of great help in forensics.

Objective: To establish an effective phenol-chloroform method coupled with paramagnetic particle method for human DNA extraction from maggot crop contents in STR genotyping., Methods: Human DNA was extracted from the maggot crop contents using phenol-chloroform method and purified by paramagnetic particle method. DNA was quantified by PCR with Quantifiler Human DNA Quantification Kit using 7500 real-time fluorescence quantitative PCR instrument. PCR products were genotyped by AmpFlSTR Identifiler PCR Amplification Kit using 3130XL-Avant genetic analyzer., Results: The template DNA yield by the method described were increased at least 2 times than the phenol-chloroform extraction method alone. All of the full 16 STR profiles could be obtained with the samples extracted by this method when the DNA yield reached (0.218 +/- 0.041) ng/microL., Conclusion: Phenol-chloroform method coupled with paramagnetic particle method can effectively increase the sensitivity of STR analysis of human DNA recovered from maggot crop contents and is a valuable tool for forensic entomology.

Molecular biology tools have enhanced the capability of the forensic scientist to characterize biological evidence to the point where it is feasible to analyze minute samples and achieve high levels of individualization. Even with the forensic DNA field's maturity, there still are a number of areas where improvements can be made. These include: enabling the typing of samples of limited quantity and quality; using genetic information and novel markers to provide investigative leads; enhancing automation with robotics, different chemistries, and better software tools; employing alternate platforms for typing DNA samples; developing integrated microfluidic/microfabrication devices to process DNA samples with higher throughput, faster turnaround times, lower risk of contamination, reduced labor, and less consumption of evidentiary samples; and exploiting high-throughput sequencing, particularly for attribution in microbial forensics cases. Knowledge gaps and new directions have been identified where molecular biology will likely guide the field of forensics. This review aims to provide a roadmap to guide those interested in contributing to the further development of forensic genetics.

This research investigates factors influencing the transfer of DNA to handled objects and the process known as 'shedding'. Volunteers were recruited to hold sterile plastic tubes using experiments originally designed by Lowe et al. [A. Lowe, C. Murray, J. Whitaker, G. Tully, P. Gill, The propensity of individuals to deposit DNA and secondary transfer of low level DNA from individuals to inert surfaces, Forensic Sci. Int. 129 (2002) 25-34]. Transferred cellular material was collected from the tubes and STR profiles generated using the AmpFlSTR SGM Plus multiplex with 28 and 34 PCR cycles. Volunteers were asked to hold the tubes with each hand, and to participate in a series of handwashing experiments. The DNA profiling results obtained from the transferred skin cells were compared. An attempt was made to characterize the volunteers as 'good' or 'bad' shedders and to establish which, if any, of the experimental variables were associated with 'good' shedding. Our results suggest that many factors significantly influence shedding, including which hand an individual touches an item with and the time that has elapsed since they last washed their hands. We have found that it may be more complicated than previously reported to categorise a person as being either a 'good' or a 'bad' shedder and that if truly 'good' shedders exist they may be significantly rarer than some have estimated. In the current research no 'good' shedders were observed in a group of 60 volunteers. Given these results, it seems that rather than being applied to individual forensic cases, knowledge of shedding characteristics will be most useful in providing general background data for the interpretation of trace DNA evidence.

Evidentiary items sometimes contain an insufficient quantity of DNA for routine forensic genetic analysis. These so-called low copy number DNA samples (< 100 pg of genomic DNA) often fall below the sensitivity limitations of routine DNA analysis methods. Theoretically, one way of making such intractable samples amenable to analysis would be to increase the number of starting genomes available for subsequent STR (short tandem repeat) analysis by a whole genome amplification strategy (WGA). Although numerous studies employing WGA have focused primarily on clinical applications, few in-depth studies have been conducted to evaluate the potential usefulness of these methods in forensic casework. After an initial evaluation of existing methods, a modified WGA strategy was developed that appears to have utility for low copy number forensic casework specimens. The method employs a slight, but important, modification of the "improved primer extension preamplification PCR" method (I-PEP-PCR), which we term mIPEP (modified-I-PEP-PCR). Complete autosomal STR and Y-STR (Y chromosome short tandem repeat) profiles were routinely obtained with 5 pg of template DNA, which is equivalent to 1-2 diploid cells. Remarkably, partial Y- and autosomal STR profiles were obtained from mIPEP-treated DNA recovered from bloodstains exposed to the outside environment for 1 year whereas non-mIPEP-treated samples did not produce profiles. STR profiles were obtained from contact DNA from single dermal ridge fingerprints when the DNA was subjected to prior mIPEP amplification but not when the mIPEP step was omitted.

Competitive PCR assays were established for the mitochondrial DNA hypervariable region I and the human amelogenin locus. Using these assays, the copy numbers of DNA participating in PCR (amplifiable DNA) were quantified in tissues exposed to different environments. Human ribs, skin and nails were left in three exposure conditions (in the open air, in soil and in water). The amounts of amplifiable DNA in these tissues were quantified during a time period of up to two months. The amount of amplifiable DNA was well preserved in hard tissues (ribs and nails) regardless of the exposure conditions, whereas the soft tissues immersed in water showed a rapid decrease in amplifiable DNA. Strong PCR inhibition was observed in the DNA extracts obtained from buried bones. This phenomenon was clearly identified from an amplification failure of the internal standards in the competitive PCR. A preliminary examination to identify the PCR inhibitor suggested that the soil itself contributed to the inhibition. In addition, the amounts of amplifiable DNA in case samples were also investigated.