Revista de investigación forense

Firearm injuries are commonly encountered by Forensic pathologists. The autopsy technique for a firearm case requires special care as the projectile has to be removed as evidence. Not all firearm injuries result in death. Survivors may carry bullets in their bodies for long periods of time as souvenirs. Souvenir or retained bullets may sometimes cause diagnostic problems regarding old or recent firearm wounds. We present a case of a firearm fatality in which a souvenir bullet was found during autopsy in a firearm victim.

In crime cases of robberies and thefts it is very important to ascertain the nature of weapon / tools involved and also the position of the locks. These details provide many vital clues regarding the modus operandi of the crime which helps the investigating agencies in solving the case. Examination of position of the lock and levers inside the lock aid in throwing light on how the crime was committed. In the present case study, the forensic examination of the breaking open of the lock of the strong room using gas cutter and arrival of conclusion based on the tool marks are discussed.

Three sets of commonly used autosomal short tandem repeat (STR) markers (containing 15, 10 and 9 markers) and 14 databases from populations belonging to Africa, America, Asia and Europe were used to investigate how the selection of the population database and the number of considered markers would influence the statistical evidence that is usually produced to favour paternity. The study was based on a sample of 100 randomly chosen Finnish paternity trios collected during paternity testing case work and without any exclusion after use of 15 STR markers. Paternity Index, Probability of Paternity, Typical Paternity Index and Probability of Exclusion were computed and descriptive statistics were provided separately for trios (mother, child and putative father) and duos (obtained from trios but not considering the genetic information of the mother). This was done for all combinations of markers and databases. In trio cases the differences between results obtained are not statistically significant. However, especially in duo cases the use of 15 STR markers is recommended.

Forensic analysts routinely encounter samples containing mixtures of DNA from male and female contributors and PCR inhibitors due to exposure to environmental insults. In order to select the appropriate STR analysis methodology for such samples and obtain optimal results at first pass, it is desirable to determine the relative quantities of male and female DNA and to detect the presence of PCR inhibitors at an early stage in the sample processing workflow. Here we describe a multiplex real-time PCR assay that can provide the desired information in a single reaction. Briefly, the simultaneous quantification of human and human male DNA is achieved by measuring the RPPH1 human target and the SRY male-specific target. At the same time a synthetic sequence is co-amplified as an Internal PCR Control (IPC) to detect the presence of PCR inhibitors. The assay has a good dynamic range (0.023–50 ng/μL) and can detect 25 pg/μL of human male DNA in the presence of ten thousand-fold excess of human female DNA. In addition, the ability of the assay to predict PCR inhibition was demonstrated by shifted IPC C T values in the presence of increasing quantities of hematin. All the real-time PCR results showed a good correlation with the downstream STR profiles obtained from a large set of various sample types therefore demonstrating that this assay can be considered a guiding tool to predict the performance of the STR genotyping kits with forensic samples.