Efficient DNA Sampling in Burglary Investigations

In terms of crime scene investigations by means of forensic DNA-analyses, burglaries are the number one mass crime in Switzerland. Around one third of the DNA trace profiles registered in the Swiss DNA database are related to burglaries. However, during the collection of potential DNA traces within someone’s residence after a burglary, it is not known whether the sampled DNA originated from the perpetrator or from an inhabitant of said home. Because of the high incidence of burglaries, crime scene investigators usually do not collect reference samples from all the residents for economical and administrative reasons. Therefore, the presumably high probability that a DNA profile belonging to a person authorized to be at the crime scene ends up being sent to a DNA database for comparison, has to be taken into account. To our knowledge, no investigation has been made to evaluate the percentage of these non-perpetrator profiles straying into DNA databases. To shed light on this question, we collected reference samples from residents who had been victims of recent burglaries in their private homes. By comparing the profiles established from these reference samples with the profiles generated from trace DNA, we can show that the majority of the DNA samples collected in burglary investigations belong to the residents. Despite the limited number of cases included in the study, presumably due to a crime decline caused by the pandemic, we further show that trace DNA collection in the vicinity of the break and entry area, in particular window and door glasses, is most promising for sampling perpetrator instead of inhabitant DNA.

Transfer of Self-Leadership Skills Within the Dutch Police: a Three-Wave Study

This three-wave study examined the training-to-work transfer process of a self-leadership skills training programme for crime scene investigators working for the Dutch police force. The transfer process is complex and depends on numerous factors. Two important steps forward are taken in the present study. First, we take into account all transfer steps in one study to gain insights into the transfer process, and second, by being specific about the work situation in which transfer outcomes should occur, we address the “criterion problem” that is often mentioned in transfer research. Based on the Ability Motivation Opportunity model, we hypothesised that the posttraining transfer process starts with being motivated to transfer and that this motivation increases the use of self-leadership during work. Another aspect that may facilitate the use of trained skills is supervisor support, as it offers opportunities to use self-leadership skills during work. In turn, self-leadership skills at work were hypothesised to lead to increased work performance. We tested our transfer model in two different work situations experienced by crime fighters. Our findings show that the use of self-leadership skills is positively related to the detached concern of crime fighters in specific situations. Additionally, our findings show that the use of self-leadership skills mediates the relation between the motivation to transfer and work performance in specific situations. Finally, our findings show that including different transfer steps (i.e. the motivation to transfer, use of skills, and performance), different performance measures, and different work situations in the transfer process provides more insight into when and how transfer-to-work after training occurs. These findings suggest that if organisations aspire to improve such transfer, then they should be specific about the intended posttraining behaviours and performance and the situations in which these outcomes should emerge.

Phase separation during blood spreading

Blood pools can spread on several types of substrates depending on the surrounding environment and conditions. Understanding the influence of these parameters on the spreading of blood pools can provide crime scene investigators with useful information. The focus of the present study is on phase separation, that is, when the serum spreads outside the main blood pool. For this purpose, blood pools with constant initial masses on wooden floors that were either varnished or not were created at ambient temperatures of $$21~^{\circ }\hbox {C}$$ 21 ∘ C , $$29~^{\circ }\hbox {C}$$ 29 ∘ C , and $$37~^{\circ }\hbox {C}$$ 37 ∘ C with a relative humidity varying from 20 to 90%. The range $$21~^{\circ }\hbox {C}$$ 21 ∘ C to $$37~^{\circ }\hbox {C}$$ 37 ∘ C covers almost all worldwide indoor cases. The same whole blood from the same donor was used for all experiments. As a result, an increase in relative humidity was found to result in an increase in the final pool area. In addition, at the three different experimental temperatures, the serum spread outside the main pool at relative humidity levels above 50%. This phase separation is more significant on varnished substrates, and does not lead to any changes in the drying morphology. This phenomenon is explained by the competition between coagulation and evaporation.

Forensic Investigation of Bullet Holes for Determining Distance from Glass Fracture Analysis

The study of glass fracture patterns has been of long interest to the forensic community. Fragments of glass can be significant evidence found in the investigation of various types of offenses especially where armed violence is involved on automobiles. Figuring out, whether glass fragments present on crime scene share the same origin as per glass that has been hit by a projectile or any substrate, is quite a success to an examiner because that further leads to the investigation of how and by which means it has done. Holes occurred in the glass at the crime scenes have much importance and many attempts are taken to investigate the properties of these glass holes to find the type, speed, and angle of the projectile which probably produce the hole. For highvelocity projectiles including bullets, these bullet holes in glass can exhibit certain features and fractures. The objective of this research was to determine the distance of shooter from the bullet hole on glass used in automobiles. Bullet holes were prepared and different parameters of glass fractures like bullet hole diameter, cone fractures radius, cone fractures diameter, radial, and concentric fracture count were considered from both front and the backside of the glass. These parameters were observed and analyzed to determine the dependency of these parameters on the variable “distance”. The consistency found in the measurements to conclude our results were checked by goodness of fit test. The study bears great significance as it could lay down a foundation to set a standard parameter to estimate distance of bullet hole from shooter in firing incidents involving glass fracture. This will provide a blueprint to crime scene investigators in order to reconstruct the crime scene for understanding and to take investigation to logical conclusion.

Phase Separation During Blood Spreading

Blood pools can spread on several types of substrates depending on the surrounding environment and conditions. Understanding the influence of these parameters on the spreading of blood pools can provide crime scene investigators with useful information. The focus of the present study is on phase separation, that is, when the serum spreads outside the main blood pool. For this purpose, blood pools with constant initial masses on wooden floors that were either varnished or not were created at ambient temperatures of 21 °C, 29 °C, and 37 °C with a relative humidity varying from 20 % to 90 %. The range 21 °C to 37 °C covers almost all worldwide indoor cases. The same whole blood from the same donor was used for all experiments. As a result, an increase in relative humidity was found to result in an increase in the final pool area. In addition, at the three different experimental temperatures, the serum spread outside the main pool at relative humidity levels above 50 %. This phase separation is more significant on varnished substrates, and does not lead to any changes in the drying morphology. This phenomenon is explained by the competition between coagulation and evaporation.

Crime Scene Investigation Issues: Present Issues and Future Recommendations

Crime Scene Investigation is the backbone of any criminal investigation. Expert report generated by Crime Scene Investigators are based on scientific evidence and are reported in a standard form. The content, when published should be reviewed rigorously by its peers. The expert report is a document detailing out how the investigation process of a crime scene was performed. The process of collecting and evidence processing do not only entail identifying, collecting and storing evidences for later analysis but it is a step by step process that is well structured in a document called Standard Operating Procedure (SOP) for Crime Scene Investigator. SOP is a complex document and sometimes overwhelmingly technical for the uninitiated. But if understood, it can be a good guide for law practitioners to determine if a piece of evidence should be included in a case. This article details out the SOP which entails groundwork before entering a crime scene, processing of a crime scene and wrapping up of the crime scene investigation. At each step, this paper will look at how it is adopted in current practices, its weakness and suggested improvement that should be adopted to ensure a final quality expert report.

RESEARCH ON MODERN FORENSIC METHODS OF DETECTION, RECORD, SEIZURE OF SHOEPRINTS AND THEIR FURTHER ACCOUNTING FOR CRIME DETECTION

Shoe prints that have been traced by crime scene investigators at the crime scene can provide information relating to a criminal or a group of criminals that have committed it, and serve as evidence while pre-trial investigation. Furthermore, shoe prints provide information on the possible participation of the same person in different types of crimes (to integrate crimes). At present, the number of crimes related to stealing civilian properties, including robbery, has significantly increased as a result of economic crisis in many countries around the world. As the studies and the practical experience while investigating crime scenes by police in many countries show, footwear evidence as much as physical evidence have not been given due attention. In order to improve the quality of crime scene examination when seizing traces of shoes, the quality of removed traces of shoes, and, as a consequence, increase the efficiency of crime detection using traces of shoes, there is a necessity in: Introduction of modern forensic tools and methods for detecting, seizing traces of shoes, and further comparative research. Establishment of the Unified National Automated System at the legislative level for accounting and identification of shoeprints seized from unsolved crime sites. Creating professional forums to share experiences with leading international forensic experts. Establishing the terms for traces and shoeprints storage and use registered (for example, not more than two years from the date of registration) at the legislative level. In addition, implementation and development of automatic database systems with the ability to conduct identification between shoeprints evidence seized from different crime scenes can provide the investigator with significant information on the possible involvement of the same person in commission of different crimes (to combine crimes), conduct so-called forensic intelligence. A shoeprint as a single piece of evidence may not be weighty enough but combined with additional evidence it is vital for detecting and investigating a crime. In conclusion, it should be noted that this area has great prospects for development and, undoubtedly, should be addressed by forensic experts in this field.

Recovery of latent fingermarks from burial environments

Background Fingermarks can be found both in indoor and outdoor crime scenes. The latter could be subjected to various types of environmental insults. In many cases, criminals try to dispose of or conceal the evidence in several ways, such as throwing in the waterways or burying in the soil to avoid detection from the law enforcement agencies. Thus, crime scene investigators often face challenges to detect and develop latent fingermarks in such environments. This study aimed to investigate the persistence and ageing of latent fingermarks in a burial environment for particular periods. To date, there is a limited study that attempted to investigate the survivability of fingermarks in a burial environment. Methodology The experiment was carried out in two settings: preliminary and main experiments. A preliminary experiment was conducted indoor to determine the most effective chemical for fingermark development on buried metal substrates. Five different chemicals were employed to develop the latent fingermarks, namely fingermark powder dusting, small particle reagent (SPR), Sudan black, oil red O, and crystal violet. The main experiment was carried out to simulate the realistic situation in which the metal substrates bearing latent fingermarks were buried in the soil within 2 months period. In both experiments, the substrates were buried in peat soil at a depth of 10 cm from the surface. Results The results demonstrated that latent fingermarks could be effectively recovered after being buried in the soil up to 8 weeks using Sudan black. The position of the substrates whether underlying in “face up” or “face down” orientations when buried had also influenced the quality of the developed fingermarks. Fingermarks buried in the “face up” position demonstrated better quality and more ridge details as compared to those buried in the “face down” position. Secondary fingermarks were also observed in this study and found to be useful for identification and must be taken into consideration when developing fingermarks on buried items in forensic cases. Conclusion The development of fingermarks recovered from burial environments is feasible as excellent ridge characteristics can still be identified. Hence, any evidence recovered from burial sites should be examined for fingermarks and cannot be discounted.

Analysis of Alternative Food Sources for Rearing Entomological Evidence

Forensic entomology is a well-established tool for evaluating the death, or abuse, of a person. Insect evidence provides valuable information as related to time of colonization and movement of remains from one location to another. Blow flies (Diptera: Calliphoridae) are commonly found on human remains throughout most stages of decomposition, and when entomological evidence is collected these taxa tend to be the most numerous. However, very few crime laboratories across the country have collection and rearing protocols for these forensically important insects. A lack of knowledge in collection techniques and limited access to an appropriate food source are the main reasons for absence in adequate collection and rearing protocols. Thus, when crime scene investigators or pathologists collect insects, they are often mishandled (e.g., placed into containers with no air holes, no food, or a food source that is not sustainable for their development). To address this issue, we analyzed easily accessible and cost-efficient alternative food sources for blow flies; specifically, tuna and wet cat food compared to beef liver (control). Survivorship and development were examined for each food source using the blow flies Phormia regina (Meigen) (Diptera: Calliphoridae) and Cochliomyia macellaria (Fabricus) (Diptera: Calliphoridae). These findings provide an overview of possible alternatives that could be used as a sustainable food source in crime laboratories when immediate action from a forensic entomologist cannot be obtained.