Investigation into "normal" background DNA on adult necks: implications for DNA profiling of manual strangulation victims

Others have investigated the role that DNA profiling could play as a method for identifying the perpetrator of manual strangulation. These studies have demonstrated that it is possible to collect offender DNA from the skin surface of a victim following physical contact. It is not known whether nonself biological material is normally present on the skin surface due to adventitious transfer occurring during innocent everyday interactions. To test the hypothesis that detectable amounts of nonself DNA are normally present on the skin surface of healthy adult individuals due to the adventitious transfer of DNA occurring during normal day-to-day social interactions, we designed an experiment in three phases. Phase 1 was used to deduce which DNA collection, extraction, and amplification methods were suited to investigating this question. During phase 2, the neck surface of 24 healthy adult volunteers was swabbed. DNA was extracted using the QIAamp DNA mini kit and amplified using the SGM Plus PCR amplification kit, using 28 PCR cycles. The work carried out during phase 3 involved a simulated assault to investigate primary and secondary transfer of DNA during physical contact. It was found that 23% of neck areas swabbed during phase 2 of this investigation showed nondonor alleles in the resulting DNA profile, with 5% of areas showing six or more nondonor alleles. The results of phase 3 showed that primary, secondary, and zero transfer of victim and/or offender DNA could be observed after physical contact and that alleles from an unknown source could still be detected in this more controlled experiment. The data presented in this paper demonstrate that DNA profiles generated after swabbing the skin surface of healthy adults can include components of an unknown source, present due to adventitious transfer. These components, if present in large quantities, have the potential to interfere with DNA profile interpretation of swabs taken for the investigation of physical assault by DNA profiling.     

Comparison of handmarks in manual strangulation: an experimental study

A police case with a strangulated woman with fingermarks on the neck and two suspects identifying each other as the perpetrator set off a laboratory experiment. Twenty-one males participated in the study. Blue paint was applied to their fingers, after which they grasped a neck dummy and pressed hard as if strangulating someone. The imprint was removed from the dummy, and their hands were photographed. Five imprints were randomly chosen and superimposed on the hand photographs in blind trials. In no cases did we match an imprint to the correct hand. However, in four cases we matched the imprint with several hands, one of which was the correct one. This means we were able to exclude nonmatches in 4/5 cases. Overall, matching of hands and fingermarks is difficult and inconclusive. Objective criteria for matching are difficult to establish, and matching is probably best suited for cases with specific anatomical features.     

Skull Fracture with Brain Expulsion in a One-Level Jumping-Fall

Abstract:  Here presented is the case of a one-level jumping-fall with extensive skull fractures and brain expulsion. The body was found on the basement floor at the foot of the stairs. At the autopsy, the skull was extensively fractured, with about half of the brain expulsed several feet away from the body. The cause of death was established as a craniocerebral trauma with brain expulsion. The circumstances and manner of death were still unclear at that time. A low fall seemed very unlikely considering the severity of the skull and brain damage. The police investigation clearly revealed that the man, in a paranoid psychotic state, attacked his wife with a knife and then was witnessed by his children to have hit his head several times with a hammer. Afterwards, they saw him running to the top of the basement stairs and jumping to the bottom of the stairs head first.     

Perimortem or Postmortem Bone Fractures? An Experimental Study of Fracture Patterns in Deer Femora*

The determination of perimortem trauma is important for forensic anthropologists. Characteristics of bone fractures such as sharp edges, presence of fracture lines, the shape of the broken ends, fracture surface morphology, fracture angle on the Z-axis, and butterfly fractures are said to differentiate perimortem from postmortem trauma. A Drop Weight Impact Test Machine was used to break 76 deer femora of various ages since death. The results of this study suggest that the characteristics listed above are unreliable at differentiating a perimortem fracture from a postmortem fracture in a forensic case. There are, however, statistically significant differences between fresh bones broken less than 4 days old and dry bones broken 44 days or 1 year old after death.     

Blunt force cranial trauma in the Cambodian killing fields

In this paper we present a unique pattern of blunt force cranial trauma that was observed in 10 of a sample of 85 crania from a Cambodian skeletal collection comprised of Khmer Rouge victims. Initial examination of the trauma, which presents as substantial damage to the occipital with fractures extending to the cranial base, suggested the pattern was classifiable as a basilar or ring fracture. However, further investigation, including trauma analysis and historical research, revealed that this fracture type is distinctive from basilar and ring fractures. Historical data indicate that a particular execution method was the likely source of the trauma. Recognition of this trauma pattern is significant because it exemplifies the distinct fracture configuration resulting from an apparently categorical and methodical execution technique. Identification of this fracture type could potentially assist forensic investigators in the recognition of specific methods of murder or execution.     

An estimate of the proportion of drug-facilitation of sexual assault in four U.S. localities

In recent years, drugs including flunitrazepam, gamma-hydroxybutyrate, ketamine, and ethanol, have become popularly associated with drug-facilitated sexual assault. Other drugs are also candidates as factors in "drug facilitated sexual assault" (DFSA). The true extent of DFSA is not known, and is difficult to estimate. We recruited sexual assault complainants at four clinics in different parts of the U.S. to anonymously provide urine and hair specimens, and to answer questions about suspected drugging, drug use, and the sexual assault incident. Urine and hair specimens were tested for 45 drugs, including ethanol, and those pharmacologically capable of inducing sedation, amnesia, or impairment of judgment. Analytical test results were used to estimate the proportion of subjects, and the proportion of all complainants to the clinic in the same time period, who were victims of DFSA. Overall, cases of 43% of 144 subjects, and 7% of 859 complainants, were characterized as DFSA. Subjects underreported their use of drugs. The role of toxicological results and history in characterizing DFSA cases is discussed.     

Extensive Petechiae in Attempted Self-Strangulation

Abstract:  A 29-year-old Korean man reported to have been robbed, bound, and gagged by a stranger in his apartment. Clinical findings included extensive petechiae to his face and tramline patterned abrasions and ligature furrows to his neck and face as well as his wrists. Initially, no other leads in the investigation existed and a robbery was assumed to have taken place. The man eventually confessed to fabricating the story and to having self-induced the ligature marks by subluxating his jaw at the temporomandibular joint and hooking the rope closest to the back of his neck on the corner of table. The man demonstrated this unsuspected ability to law enforcement officers. As a motive for his unconventional behavior, he confessed to engaging in autoaggressive behavior as punishment for "losing face" after his ex-girlfriend terminated her pregnancy. This case demonstrates that petechiae due to neck compression also may occur in the living and are due to vascular compression and not lethal hypoxia.     

Pacemaker/defibrillator evaluation at Los Angeles County Department of Coroner*

Pacemakers and implantable cardioverter-defibrillators (ICDs) are implanted medical devices for the treatment of cardiac arrhythmias. These devices are now commonly encountered in the postmortem situation. The Los Angeles County Department of the Coroner uses the services of a cardiac electrophysiology consultant to interrogate pacemakers and ICDs, producing a detailed picture of the cardiac events recorded by the device. We have used this method to evaluate 20 cases where the ICD or pacemaker provided significant information. We report four forensic cases to illustrate the different applications of pacemaker interrogation and its contribution in forensic investigation. This technique was used to establish identification of the decedent, to determine the cause and time of death, and to determine whether device malfunction could have played a role in the death. We conclude that detailed evaluation of the pacemaker or ICD in selected cases may provide essential information to the forensic pathologist.     

Asphyxia Homicides in Finland, 1983–2012

Finland has one of the highest homicide rates in Western Europe, and almost every tenth homicide is caused by asphyxiation. Reliable statistics, a strict legislation, and an exceptionally high medico-legal autopsy rate formed a base for a nationwide analysis of asphyxia homicides (n = 383) during 30 years. The cases were identified through multiple records, and all the forensic pathology case files were studied in detail. In more than one out of five cases, there were indications of staging, and the homicide was revealed first at autopsy in close to one in ten cases. The vast majority of the homicides took place in private locations and involved persons known to each other. Every third victim was an intimate partner, and every tenth a child. Almost half of the victims died from manual strangulation, one in three from ligature strangulation. Smothering, choking, neck compression with a firm object, and thoracic compression were more rare methods. Drownings were excluded from this study material. Of all the victims, 7% had no observable external injuries. Petechiae were recorded in approximately in 61%, laryngohyoid fractures in 47%, and vocal cord hemorrhages in 16% of the cases. Every tenth female victim had genital injuries. Toxicological analyses were performed in close to all of the cases, and almost three out of four victims tested positive for blood alcohol. The various aspects of the demographics and autopsy findings covered in this study contribute reliable and accurate data to further strengthen the spectrum of observable medico-legal characteristics of asphyxia homicides.