法医学研究杂志

Non-destructive chemical method and simple methods for determining the sequence of intersecting color ballpoint pen stroke and color laser printed marking has been done. Different chemicals compounds such as pyridine, ethyl acetate, 2-phenoxyethanol, methanol, and ethyl alcohol are used to treatment glossy paper for lifting technique. These chemicals enhance the lifting technique in comparison with using glossy paper only especially with ethyl alcohol. Simple techniques such as side lighting technique depending on embossing phenomena, microscopically with both transmitted and external 45° light and absorbance/reflectance techniques are used. According to the results of the study and blind test, it is recommended that using the previous techniques should be done in the following order: lifting technique using ethyl alcohol treatment, lifting technique without treatment, side lighting (in case of presence embossing), and microscopically. Absorbance/reflectance techniques were excluded because the results obtained are misleading. All used techniques are simple, non-destructive and can be photographically demonstrated.

Fourier Transform Infrared (FTIR) spectroscopy has been shown to be a rapid, non-destructive analytical technique capable of detecting trace amounts of exogenous particulate in fresh latent fingermarks. Fingermarks identified at a crime scene however, are rarely fresh and are likely to have been deposited days or even weeks before forensic analysis, leaving them prone to decomposition.

In this study latent fingermarks were contaminated with trace amounts of the improvised explosive precursor’s ammonium nitrate and sodium chlorate, and the addictive narcotic cocaine. The latent fingermarks where then aged in natural daylight conditions over a 30 day period and intermittently analysed using FTIR spectromicroscopy. Exogenous particulate was identified using spectroscopic imaging of each fingermark, and spectra obtained from the samples were compared to control spectra to confirm the identification of the contaminant. This study demonstrates that these contaminants are detectable within latent fingermarks up to at least 30 days after deposition, with only ammonium nitrate showing signs of decomposition, and that fingermark chemistry has a minimal effect on their molecular integrity. This information has broad implications for the law enforcement community as it suggests that the detection of exogenous particulate within latent fingermarks is possible long after a suspect has handled an illegal substance. This study also confirms the use of spectroscopic imaging to provide a chemical signature for these illicit compounds weeks after deposition, and an image of the fingermark ridge pattern that can then be used for identification purposes.

The outburst of next generation sequencing has outpaced the traditional capillary electrophoresis (CE) based forensic genomics in terms of throughput, scalability and allelic resolutions. The limitations of CE-based detection system for STRs (Short Tandem Repeats) and SNPs (Single Nucleotide Polymorphisms) markers associated with forensic DNA phenotyping have been greatly overcome through next generation sequencing (NGS). It offers simultaneous analysis of forensically relevant genetic markers including STRs, SNPs, mutations and transcripts to improve efficiency, capacity and resolution through massively parallel sequencing. The detailed sequence information in comparison with ever growing DNA databases across the world may aid mixture interpretation, and will ensure enhancement in statistical weight of the evidence.

Nowadays, a total of 33 NGS machines with low to high throughput are available but two dedicated systems including MiSeq®FGx™ Forensic Genomics System (Illumina) and the HID-Ion Personal Genome Machine (PGM)™ (Thermo Fisher Scientific) offer the sequencing of customized forensically informative SNP panels. Ion torrent launches Ion S5 and Ion S5 XL (with additional feature of local computing which enhances its analysis speed) which include same core instrument. The future of forensic genomics lies with integrated high throughput approaches to solve the increasing number of cases or mass disaster studies where forensic specimens and samples are compromised and degraded. In future new real-time sequencing platforms will revolutionize the field of forensic genomics.

Fingerprints begin forming at about the 6th to the 13th week of gestation. A number of factors determine the print pattern in the womb, including the density of the amniotic fluid surrounding the foetus, the size of the foetus, the friction in the womb, the location in the womb amongst others. Once developed the pattern remains constant throughout life. Basically there are three main patterns; The Loop, which rise up and loop back around, continuing on the same direction it started from and it accounts for about 70% of all fingerprints, Arches look like waves that rise and fall on the same fingerprint pattern, accounting for 5% whiles the Whorls appear as circular patterns accounting for 25%. The loop has only one delta, the Arch no delta with the Whorl pattern having two deltas. In the case presented here, a young man of 30 years, who is physically fit and normal without any significant clinical condition apart from a developmental defect of the right thumb which makes it different from the left thumb. From the ten fingerprint patterns taken with the aid of a scanner from the subject, only the abnormal right thumb of the subject with a whorl fingerprint pattern has three deltas which are extremely uncommon and quite different to the traditional, widely known two deltas seen in all whorl patterns in fingerprints. Fingerprint deltas are only present in loops and whorls. There are basically four types of fingerprint whorls. The plain with two deltas, central pocket with two deltas, the double loop whorls with two deltas and accidental whorls which have two or more deltas. Theoretically, less than 1 in 1000 people has these extremely rare fingerprints. The three deltas in a fingerprint whorl pattern may exist in accidental whorls, but no mention is made of it in plain whorls which make this case perhaps the first ever of a known plain whorl with three deltas. This feature is very uncommon in normal patterns. In this case the thumb of this young man has developed abnormally in the womb and has a whorl pattern with three deltas. It is imperative this pattern is taken into consideration when evaluating or interpreting fingerprints. Though the number may be statistically small, it is still essential this is taken into account in manual and especially when using automatic fingerprint identification software to evaluate known and unknown fingerprints.