A Study of PCR Inhibition Mechanisms Using Real Time PCR*,†

Abstract: In this project, real time polymerase chain reaction (PCR) was utilized to study the mechanism of PCR inhibition through examination of the effect of amplicon length, melting temperature, and sequence. Specifically designed primers with three different amplicon lengths and three different melting temperatures were used to target a single homozygous allele in the HUMTH01 locus. The effect on amplification efficiency for each primer pair was determined by adding different concentrations of various PCR inhibitors to the reaction mixture. The results show that a variety of inhibition mechanisms can occur during the PCR process depending on the type of co‐extracted inhibitor. These include Taq inhibition, DNA template binding, and effects on reaction efficiency. In addition, some inhibitors appear to affect the reaction in more than one manner. Overall we find that amplicon size and melting temperature are important in some inhibition mechanisms and not in others and the key issue in understanding PCR inhibition is determining the identity of the interfering substance.     

Determining the Source of Equine Bloodstains by Dinucleotide Repeats*

Abstract: A novel multiplex of independent dinucleotide tandem repeat (DTR) loci was previously described that is capable of not only discriminating human and equine DNA, but of identifying a single equine source. We report a case in which a bloodstained syringe and two needles were found during inspection of a barn by inspectors of the Pennsylvania Racing Commissions. Using the multiplex and single‐locus detection, all 21 equine DTR markers were detected in a suspect horse and two evidence samples, indicating the evidence samples came from the suspect animal. Only six markers were detected in the third evidence sample because the volume of blood was limited. Following whole‐genome amplification and single‐locus PCR, the third evidence sample detected a total of 17 markers and the likelihood of identity (probability from suspect horse/probability from a random pacer) was 7.0 × 10⁶. The DTR multiplex has some technical limitations, but it is already practical for casework.     

Murder Followed by Suicide: A Newspaper Surveillance Study Using the New York Times Index

Abstract: Murder–suicide is a relatively uncommon event but as reported by the New York Times, it has occurred and continues to occur yearly. Previous research has indicated that those who commit murder–suicides tend to be men, are in or have been in an intimate relationship with the victim, victims tend to be women, and a firearm is most likely to be used. This study uses a newspaper surveillance methodology to examine such cases. Articles from the New York Times as found in the New York Times Index were coded, analyzed, and examined. The cases, 166 in total, support the findings from prior research. The trend data was examined by cross tabulations and chi‐square analysis. The findings suggest that murder–suicides are rare events and when they occur they usually involve a male perpetrator and an intimate partner victim who is either a wife or girlfriend with the event occurring in a private home. A firearm is the most commonly used method for both murders and suicides, particularly if there was more than one murder victim. The authors conclude by suggesting that future research should focus on using the forthcoming data resource in the CDC’s National Violent Death Reporting System (NVDRS) to examine the occurrence of murder–suicide.     

Tales of Deviance and Control: On Space,Rules, and Law in Squatter Settlements

In Latin American cities, around a third of the urban population lives in tenure situations that can be designated as informal, yet variation in the ways and extent to which these arrangements do not comply with law is extensive. Furthermore, informal dwellers often employ a variety of strategies to legitimize and ultimately legalize their tenure, implying a dynamic rather than a static relationship between illegality and legality. Conceiving of land tenure in dichotomous terms, as simply being either legal or illegal, therefore, fails to reflect this diversity, nor does it capture the evolving nature of the relationship between informal settlements and the state system. Drawing from the development of squatter settlements in Buenos Aires, this article proposes an alternative perspective and shows how settlements alternate strategies of noncompliance with adaptation to the state legal system to gradually increase their legality.     

A Checklist of Calliphoridae Blowflies (Insecta,Diptera) Associated with a Pig Carrion in Central Brazil*

Abstract: Although the Cerrado is the second major Brazilian biome, few studies have been undertaken about its entomofauna. Blowflies have an important role in forensic entomology, helping in the determination of postmortem intervals. The main goal of this exploratory study was to identify and to catalog the blowfly species associated with a pig carcass. The study was conducted in a pasture in Brasília, Distrito Federal. A pig (Sus scrofa) was killed with a .22 caliber shot in the frontal region of the head. Adult blowflies were surveyed daily from June 1 through 30, 2004. A total of 14,910 adult calliphorids were collected, representing eight species: Chrysomya albiceps, C. megacephala, Cochliomyia macellaria, Chloroprocta idioidea, Hemilucilia semidiaphana, H. segmentaria, Lucilia cuprina, and L. eximia. C. albiceps was the most frequent species, amounting to 94.76% of the catch. Five decomposition stages were observed, and for calliphorids, the most attractive stage was the bloated one.     

Ricochet of a Bullet in the Spinal Canal: A Case Report and Review of the Literature on Bullet Migration

Abstract: Ricochet of a bullet in the spinal canal is well known by neurosurgeons but relatively not a common event in usual medico‐legal autopsy practice. This article presents a homicide case of a penetrating gunshot injury of the lumbar spine through the T12‐L1 intervertebral foramen with active movement of the projectile within the spinal canal to the L5‐S1 level. This case illustrates a bullet intradural and intramedullary active movement because of a ricochet of the body of T12 with active redirection of the path. In the current literature, different types of migration in caudal or cranial direction, intradural, or intramedullary are reported. If spontaneous migration of T10 to S1 seems to be more frequent, some authors reported a C1 to S2 migration. Such migration could be asymptomatic or induce neurological impairment. The medico‐legal consequences of these migrations within the spinal canal are described.     

Crime clearance rates in Canadian municipalities: A test of Donald Black's theory of law

Donald Black's theory of law has been considered an important theory in the sociology of law. However, while the theory views law as a quantity variable, there has been limited empirical support from quantitative studies. This study offers a quantitative test of Black's theory using data from 579 Canadian municipalities. The results show that the quantity of law, in terms of crime clearance rates, varies positively with stratification, morphology, culture, and organization just as Black's theory has predicted. In addition, population size, population density, the property and violent crime rates, and policing resources also affect the clearance rates. These findings support the general notion that there is more law for certain groups and under certain social conditions. Also, most of the findings are consistent with Black's theory, thus supporting its viability as a sociological theory. In addition, two seemingly contradictory explanations, the resource explanation and the need/dependency explanation, are proposed to interpret the findings. These contradictory and yet complementary explanations perhaps reflect the reality of law in society.