ORO. The Physical Developer replacement?

In the process of fingerprint development Physical Developer has been largely the method of choice on porous surfaces after coming into contact with wet environments. It is only recently that a new technique has been identified which could replace this standard technique. This study aims to build on previous research and expand knowledge regarding the technique. The study built on previous research and compared Physical Developer to Oil Red O, testing both on four paper types, while being placed in three different water types and an accelerant for various amounts of time. Marks were placed with both heavily ‘loaded’ sebaceous fingers and ‘normal’ un-washed fingers. Results show that Oil Red O consistently produced clearer more detailed marks from the ‘loaded’ fingers, but neither technique proved to work better on the ‘normal’ marks. Neither technique developed any prints from the accelerant.     

The effects of tougher enforcement on the job prospects of recent Latin American immigrants

Attempts to enforce immigration laws in the U.S. interior have proliferated in recent years, yet the effects of these laws on immigrants are largely unknown. This paper examines whether increases in immigration‐related law enforcement since 2001 have adversely affected the labor market outcomes of low‐education male immigrants from Latin America, a group that comprises the bulk of undocumented workers in the U.S. The crackdown on the use of fraudulent Social Security numbers, increased requirements for government‐issued identification, and other changes associated with greater focus on national security likely lowered the demand for undocumented foreign‐born workers in the years following the 9/11 terrorist attacks. Using Current Population Survey data and a difference‐in‐differences estimation technique, we find strong evidence of worse labor market outcomes among recent Latin American immigrants in the post‐9/11 period relative to natives and prior Latin American immigrants. The results indicate a decline in employment, hours worked, and earnings among recent male Latin American immigrants relative to similarly low‐skilled black and Hispanic natives and vis‐à‐vis Latin American immigrants who have been in the U.S. longer. Our findings are consistent with firms increasingly substituting legal workers for undocumented labor in the years following 9/11. © 2009 by the Association for Public Policy Analysis and Management.     

Evaluation of the Differex™ System

Differential extraction is an efficient method to separate sperm cells from epithelial cells. A manual Chelex^®-100 based method is used at the Swedish National Laboratory of Forensic Science, SKL. The Differex™ System (Promega) uses a Proteinase K digestion of epithelial cells followed by centrifugation and phase separation. The sperm- and epithelial fractions are further purified with DNA IQ™ System (Promega) or with phenol/chloroform. The Differex™ System in combination with DNA IQ™ System were evaluated and compared to the Chelex^®-100 method used routinely. After modifications, the Differex™ System gave comparable results to the Chelex^®-100 method. The modifications included additional Proteinase K and DTT, longer incubation time and additional steps when removing the solid support from the Digestion Solution. In the Chelex^®-100 based method microscopic examination is done on the sperm pellet in a total volume of 50 μl. It was not possible to do a microscopic examination in less than 100 μl using the Differex™ System. Additionally the sperms were in clusters of epithelial cell debris. Microscopic examination is an important part of the differential extraction at SKL. Therefore, the Differex™ System will not be implemented at our laboratory.     

Analyzing the Dynamics and Morphology of Cast‐off Pattern at Different Speed Levels Using High‐speed Digital Video Imaging

During a bloodstain pattern analysis, one of the essential tasks is to distinguish between different kinds of applied forces as well as to estimate their level of intensity. In this study, high‐speed digital imaging has been used to analyze the formation of cast‐off patterns generated by a simulated backswing with a blood‐bearing object. For this purpose, 0.5 mL blood was applied evenly over the last 5 cm of a blade simulant. Bloodstains were created through the controlled acceleration of a backswing at different speed levels between 1.1 m/sec and 3.8 m/sec. The flight dynamics of blood droplets were captured with an Olympus^® i‐Speed 3 high‐speed digital camera with a Nikon^® AF Nikkor 50 mm f/1.8 D lens and analyzed using the Olympus i‐Speed 3 Viewer software. The video analysis showed that, during the backswing, blood droplets would move toward the lower end of the knifepoint and would be tangentially thrown off. These droplets impacted on the horizontal surface according to the arc of the swing. An increase in velocity led to longer cast‐off patterns with distinct morphological characteristics. Under laboratory conditions, bloodstain pattern analysis allows certain conclusions about the intensity of a backswing and provides instructions on the position of the offender. However, due to the number of unknown variables at a crime scene, such interpretation of cast‐off patterns is extremely limited and should be performed with extreme caution.     

When Both Sides are Mistaken: Layperson and Legal Professionals’ Misconceptions of Canadian Suspects’ Legal Rights Upon Arrest

Canadian criminal suspects have notably limited access to legal counsel upon arrest compared to suspects in the U.S. Additionally, prior research has shown significant misunderstanding of police warnings informing suspects of their rights upon arrest. This paper presents three studies on Canadians’ comprehension of criminal suspects’ rights upon arrest, with a focus on the right to counsel. Study 1 (N=80) and Study 2 (N=377) examined Canadian layperson’s comprehension, knowledge, and perceptions of legal rights upon arrest. In turn, Study 3 (N=78) investigated Canadian legal professionals’ perceptions of laypersons’ knowledge of those rights. Results from these three studies indicated there is substantial confusion about the right to counsel for Canadian criminal suspects. These results also support previous research demonstrating problems with comprehension of Canadian police cautions. Taken together, the findings of the present research pose significant concern for an increased risk of false confessions from Canadian suspects who enter an interrogation with limited knowledge and understanding of their legal right to counsel.     

Explaining Dosage Diffusion During Hot Spot Patrols: An Application of Optimal Foraging Theory to Police Officer Behavior

Drawing from the concepts of optimal foraging theory, this paper presents and tests the assumptions of a foraging theory of police behavior during hot spots patrols. The theory explains why, over time, officers involved in hot spots policing interventions would leave the hot spots they are assigned to police and begin working within other locations. We test what factors influence the amounts of activity that officers undertake outside of their assigned hot spots and at nearby streets using data gathered as part of the Philadelphia Foot Patrol Experiment. Officers performed more activity outside of their beats as the experiment progressed. Several theoretically relevant variables predict the level of activity that officers perform outside their beats, including the size of the target area and the amounts of crime occurring within and outside of the target area. “Dosage diffusion” might be one reason why hot spot interventions have diminishing effects over time. From an optimal foraging theory perspective, hot spots requiring police officers to constrain their actions to pre-defined areas can be perceived as counter-intuitive by the officers, especially over extended periods of time. The results of this study support the suggestion that hot spots patrols should be short-term and randomly rotated across hot spots.