Metal objects mapping after small charge explosions. A study on AISI 304Cu steel with two different grain sizes

Evidence of exposure of a metal component to a small charge explosion can be detected by observing microstructural modifications; they may be present even if the piece does not show noticeable overall plastic deformations. Particularly, if an austenitic stainless steel (or another metal having a face-centered cubic structure and a low stacking fault energy) is exposed to an explosive shock wave, high-speed deformation induces primarily mechanical twinning, whereas, in nonexplosive events, a lower velocity plastic deformation first induces slip. The occurrence of mechanical twins can be detected even if the surface is damaged or oxidized in successive events. In the present research, optical metallography (OM) and scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) were used to detect microstructural modifications caused on AISI 304Cu steel disks by small-charge explosions. Spherical charges of 54.5 or 109 g TNT equivalent mass were used at explosive-to-target distances from 6.5 to 81.5 cm, achieving peak pressures from 160 to 0.5 MPa. Explosions induced limited or no macro-deformation. Two alloy grain sizes were tested. Surface OM and SEM evidenced partial surface melting, zones with recrystallization phenomena, and intense mechanical twinning, which was also detected by STM and X-ray diffraction. In the samples' interior, only twins were seen, up to some distance from the explosion impinged surface and again, at the shortest charge-to-sample distances, in a thin layer around the reflecting surface. For forensic science locating purposes after explosions, the maximum charge-to-target distance at which the phenomena disappear was singled out for each charge or grain size and related to the critical resolved shear stress for twinning.     

Damage caused to fibres by vapour cloud explosions

Research on the very specific damage to single textile fibres caused by vapour cloud explosions is presented. Vapour cloud explosion experiments were carried out using a selection of 41 garments differing in colour, fibre composition and textile construction. Fibres subjected to a vapour cloud explosion become wider at the end, often taking the form of a ball, bulb or shovel, while the morphological structure of the remaining part of the fibre remains almost unchanged. The presented results can clearly indicate that an explosion took place at the scene of the crime. The authors would like to be able to provide investigators with specific information on how to link clothes (and thus people) to a specific type of crime.     

Determining explosivity part II: comparison of small-scale cartridge tests to actual pipe bombs

The small-scale explosivity device (SSED) has been used to assess the explosive power of a number of low explosives-smokeless powders (WC-870, Red Dot, Bullseye, Winchester Action Pistol, and IMR-PB), Pyrodex, black powder, and an improvised explosive (TATP). The device requires 2 g of energetic material, a heavy-walled containment vessel, and a standard blast shield to permit use in most laboratories. The data from the SSED are compared with the fragmentation of pipe bombs which contained 300 to 700 g of powder. The SSED provided the same relative ordering of explosivity as suggested by the fragmentation of the real devices. In addition, the SSED was used to evaluate the chemical residue remaining after an explosion. Issues in using the device such as optimal detonators and restricted reaction volume were probed using three high explosives--TNT, Tetryl, and RDX.     

Physical and chemical evidence remaining after the explosion of large improvised bombs. Part 2: Firings of calcium ammonium nitrate/sugar mixtures

Six test firings of large improvised explosive devices were carried out. The principal objectives of the firings were to measure the physical effects of the explosions upon representative objects placed nearby and to recover any chemical traces deposited on these objects. The results are intended for use as an aid in determining the approximate size and type of an explosive employed in terrorist attacks. Three 454 kg charges of a mixture of calcium ammonium nitrate (CAN) fertilizer and sugar, and three 2268 kg charges of a similar mixture, all confined in cylindrical steel containers were fired. Each charge was surrounded by 19 road signs mounted on posts and four vehicles, to act as witness materials. The analysis of aqueous swab extracts taken from the witness materials after firing showed the recovery of nitrate, ammonium and low levels of glucose. No sucrose was detected. Nitrate was usually recovered in greater quantities than ammonium and recovery generally decreased with increasing distance from the charges in any given direction. Quantities recovered from objects placed at the same distance in different directions varied considerably. Patterns of physical damage to the witness materials could be discerned according to their distance from the charge and the size of the charge. The velocities of detonation and air blast effects were measured.     

Aerosol or IED explosion: a case report

The Punjab State has witnessed quite a large number of explosions caused by terrorists for more than one and half decades. Conseqently, any incident of an explosion in the state gives the impression of having resulted from terrorist activity. The authors examined the scene of occurrences and carried out laboratory examinations. The quantitative estimation of the aerosol mixture formed from the LPG leaked from the cylinder and the volume of space available is within the critical limits of explosive forming mixture, has substantiated the explosion due to the leakage of LPG.     

The Anatomy of a Pipe Bomb Explosion: Measuring the Mass and Velocity Distributions of Container Fragments

Improvised explosive devices such as pipe bombs are prevalent due to the availability of materials and ease of construction. However, little is known about how these devices actually explode, as few attempts to characterize fragmentation patterns have been attempted. In this study, seven devices composed of various pipe materials (PVC, black steel, and galvanized steel) and two energetic fillers (Pyrodex and Alliant Red Dot) were initiated and the explosions captured using high‐speed videography. The video footage was used to calculate fragment velocities, which were represented as particle velocity vector maps. In addition, the fragments were weighed. The results demonstrate a correlation between the type of energetic filler and both the size and velocity of the fragments. Larger fragments were produced by Pyrodex filler indicating a less complete fragmentation, compared with smaller fragments produced by double‐base smokeless powder. Additionally, higher fragment velocities were seen with Alliant Red Dot filler.     

Explosion-related deaths in Sweden--a forensic-pathologic and criminalistic study

All cases of death caused by explosions of explosive solids, fluids and gases in Sweden during the 6-year period 1979-1984 were analyzed. Among the total of 61 fatalities 33 (54%) were due to accidents (2/3 of them occupational and 1/3 miscellaneous accidents), 25 (41%) were suicides, and only 3 (5%) were associated with terrorist activity. About one half of the occupational accidents were caused by deficient safety devices or defective equipment, while the other half was due to transgression of regulations. All suicides were males, relatively elderly, the majority of them burdened with somatic and mental diseases, alcoholism, social or economical problems, most of them being familiar with explosives. The anatomical localization of suicidal explosive injuries was regular and symmetric, while the accidental and terrorist injuries showed great variations. The terrorist-associated deaths had common features different from all other death cases, strongly suggesting the same type of bomb and the same terrorist group. Explosives caused only superficial burns or singes. Symmetric hemorrhages of the vocal folds and fracture of the laryngeal skeleton were found, as well as ruptures of trachea and lungs. When not ruptured, the lungs showed to different types of injury: hyperinflation, probably due to the blast-induced barotrauma to the respiratory passages, or lung contusions. In cases of suspected terrorist explosions close collaboration between the forensic pathologists and police investigators is mandatory since the bodies of victims protect parts of the bomb from fire or from being spread over a larger area and thus constitute a part of the crime scene.     

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.     

Muscle contraction during electro-muscular incapacitation: A comparison between square-wave pulses and the TASER(®) X26 Electronic control device

Abstract: Electronic control devices (including the Advanced TASER^® X26 model produced by TASER International) incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, effects of monophasic square waves with different parameters were compared with those of the X26 electronic control device, using two animal models (frogs and swine). Pulse power, electrical pulse charge, pulse duration, and pulse repetition frequency affected muscle contraction. There was no difference in the charge required, between the square waveform and the X26 waveform, to cause approximately the same muscle‐contraction response (in terms of the strength‐duration curve). Thus, on the basis of these initial studies, the detailed shape of a waveform may not be important in terms of generating electro‐muscular incapacitation. More detailed studies, however, may be required to thoroughly test all potential waveforms to be considered for future use in ECDs.     

Pathologic features of suicidal deaths caused by explosives

Suicidal explosions that lack a terrorist background are only rarely encountered in the field of forensic pathology. The investigation of explosion-related fatalities can be a substantial challenge in medicolegal casework. Determining whether the manner of death is suicide, homicide, or accident in such cases can present an especially difficult task to the forensic pathologist. This study considers the pathologic features of suicidal deaths caused by explosives without a terrorist background. The modus operandi of the decedents reflected familiarity and proficiency, or at least a degree of specialized knowledge, with the construction and use of explosive devices. All explosions were set off in confined spaces. The injury patterns consisted of a combination of primary blast injuries (e.g. decapitation, traumatic amputation of limbs, gross lacerations of the body surface, blast injuries of gas-containing and hollow organs), secondary blast injuries (e.g. splinter-induced penetrating trauma), tertiary blast injuries (e.g. abrasions and contusions), and burn injuries (mostly of the flash type). The previously described symmetric distribution pattern of injuries in suicidal explosions was apparent only to a certain degree in the present series. Our observation of superficially sharp-edged wound margins with bridging in the depths of the lesion in blast-induced lacerations of the skin should deserve further attention in forthcoming cases of explosion-related fatalities because this finding is a diagnostic possibility that may support the theory of an explosion-related fatality under special circumstances, e.g. when the body has been dumped away from the place of death. Because a terrorist attack may be initially suspected in each case of suicide involving explosives, the importance of a joint inquiry based on expertise from police investigators, bomb experts, and forensic pathologists is evident.     

Medical devices; retention in class III and effective date of requirement for premarket approval for three preamendments class III devices--FDA. Proposed rule; opportunity to request a change in classification

The Food and Drug Administration (FDA) is proposing to retain in class III, three preamendments class III medical devices, and is proposing to require the filing of a premarket approval application (PMA) or a notice of completion of a product development protocol (PDP) for these devices. FDA believes that the suction antichoke device, the tongs antichoke device, and the implanted neuromuscular stimulator device should remain in class III because insufficient information exists to determine that special controls would provide reasonable assurance of their safety and effectiveness, and/or these devices present a potential unreasonable risk of illness or injury. The agency is summarizing its proposed findings regarding the degree of risk of illness or injury designed to be eliminated or reduced by requiring the devices to meet the statute's approval requirements and the benefits to the public from the use of the devices. In addition, FDA is announcing the opportunity for interested persons to request the agency to change the classification of any of the devices based on new information.     

Toxicological investigation of liquid petroleum gas explosion: human model for propane/ethyl mercaptan exposures

Four individuals died as the result of a propane explosion. As with many propane explosions, the question was raised as to the adequacy of the product's odorization after the autopsy studies had been conducted. In most cases, this question leads to litigation. Ethyl mercaptan is a widely used odorant for propane and was used in this instance. Three of the four victims had blood available at autopsy for study. Quantitative analyses of the victims' blood, obtained during autopsy, were performed using gas chromatography/mass spectrometry, without subjecting the samples to hydrolysis. These analyses determined the relative amounts of propane and ethyl mercaptan in the blood to be 90, 63, and 175 mL/m3 headspace, and 0.36, 0.34, and 0.77 microgram/L blood, respectively. Since mercaptans have been reported in human blood as products of metabolism, modeling studies were conducted to establish the validity of the autopsy data and to develop an autopsy toxicology protocol for investigating explosion deaths. When subjects were not exposed to an atmosphere containing ethyl mercaptan, dimethylsulfide was the only mercaptan detectable in their blood without severe hydrolysis prior to analysis. Metabolic ethyl mercaptan is sufficiently bound to be undetectable by the methods used without hydrolysis. Human subjects were exposed to a flammable mixture of air and propane odorized with ethyl mercaptan. The analyses of the blood from these subjects produced results which were comparable with those for the explosion victims, establishing that the question of odorant adequacy can be addressed at the autopsy of propane explosion victims. It is extremely important that the pathologist and toxicologist investigating gas explosion deaths recognize the valuable evidence existing in the victim's blood.     

Explosion Scene Forensic Image Interpretation

Image interpretation is an important aspect in the field of forensic science; however, it is seldom reported how to use these techniques in explosion scene forensic investigations. On 12 August 2015, a series of explosions killed 165 people and injured hundreds more at a container storage station at the Port of Tianjin. In this study, we applied image interpretation methods to determine the seat of the explosion by analyzing low‐quality video clips of the event. The interpretation fits well with recently published standard operating procedures, including the hypothesis, evaluation, inference, and confirmation. Image processing was adopted to enhance the images while the explosion scene was reconstructed with the same images. Some important features were extracted and utilized to distinguish whether the flashes were caused by reflection or a real blast. We reveal the real explosion location, which guides the overall investigation. The results indicate that image interpretation is a powerful tool for forensic investigators to analyze low‐quality images in complicated explosions or fire accidents.     

Linking ammonium nitrate-aluminum (AN-AL) post-blast residues to pre-blast explosive materials using isotope ratio and trace elemental analysis for source attribution

Forensic science practitioners are often called upon to attribute crimes using trace evidence, such as explosive remnants, with the ultimate goal of associating a crime with a suspect or suspects in order to prevent further attacks. The explosive charge is an attractive component for attribution in crimes involving explosives as there are limited pathways for acquisition. However, there is currently no capability to link an explosive charge to its source via post-blast trace residues using isotope ratios or trace elements. Here, we sought to determine if pre-blast attribution signatures are preserved after detonation and can be subsequently recovered and detected. A field study was conducted to recover samples of post-blast explosives from controlled detonations of ammonium nitrate-aluminum (AN-Al), which were then analyzed via isotope ratio mass spectrometry (IRMS) and inductively coupled plasma-mass spectrometry (ICP-MS) for quantitation and profiling of isotopes ratio and trace element signatures, respectively. Oxygen and nitrogen isotope ratios from AN-Al yielded some of the most promising results with considerable overlap within one standard deviation of the reference between the spreads of pre- and post-blast data. Trace element results from AN-Al support the findings in the isotope ratio data, with 26 elements detected in both pre- and post-blast samples, and several elements including B, Cd, Cr, Ni, Sn, V, and Zn showing considerable overlap. These preliminary results provide a proof-of-concept for the development of forensic examinations that can attribute signatures from post-blast debris to signatures in pre-blast explosive materials for use in future investigations.     

Nonterrorist suicidal deaths involving explosives

Suicidal deaths involving explosives unconnected to terrorism are rare. The investigation of deaths from explosive devices requires a multidisciplinary collaborative effort, as demonstrated in this study. Reported are 2 cases of nonterrorist suicidal explosive-related deaths with massive craniocerebral destruction. The first case involves a 20-year-old man who was discovered in the basement apartment of his father's home seconds after an explosion. At the scene investigators recovered illegal improvised power-technique explosive devices, specifically M-100s, together with the victim's handwritten suicide note. The victim exhibited extensive craniofacial injuries, which medicolegal officials attributed to the decedent's intentionally placing one of these devices in his mouth. The second case involves a 46-year-old man who was found by his wife at his home. In the victim's facial wound, investigators recovered portions of a detonator blasting cap attached to electrical lead wires extending to his right hand. A suicide note was discovered at the scene. The appropriate collection of physical evidence at the scene of the explosion and a detailed examination of the victim's history is as important as documentation of injury patterns and recovery of trace evidence at autopsy. A basic understanding of the variety of explosive devices is also necessary. This investigatory approach greatly enhances the medicolegal death investigator's ability to reconstruct the fatal event as a means of separating accidental and homicidal explosive-related deaths from this uncommon form of suicide.     

Pulse Variations of a Conducted Energy Weapon (Similar to the TASER® X26 Device): Effects on Muscle Contraction and Threshold for Ventricular Fibrillation*

Abstract: Conducted energy weapons (such as the Advanced TASER X26 model produced by TASER International), incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, a “Modifiable Electronic Stimulator” was used to evaluate the effects of changing various parameters of the stimulating pulse. Muscle contraction was affected by pulse power, net/gross charge, pulse duration, and pulse repetition frequency. The contraction force increased linearly as each of these factors was increased. Elimination of a precursor pulse from X26‐like pulses did not have a significant effect on the normalized force measured. Muscle‐contraction force increased as the spacing increased from 5 to 20 cm, with no further change in force above 20 cm of spacing. Therefore, it is suggested that any future developments of new conducted energy weapons should include placement of electrodes a minimum of 20 cm apart so that efficiency of the system is not degraded. In the current study, the 50% probability of fibrillation level of X26‐like pulses ranged from 4 to 5 times higher than the X26 itself. Relatively large variations about the X26 operating level were found not to result in fibrillation or asystole. Therefore, it should be possible to design and build an X26‐type device that operates efficiently at levels higher than the X26.     

Suicide by explosion of natural gas: case report and review of literature

Natural gas (NG) is used as a home energy supply and, with or without ignition, is rarely misused to result in death. The authors report an unusual suicidal explosive death induced by NG. A huge explosion with resultant fire had blown out a bungalow, with destructive damage predominantly above the ground, resulting in only 1 exterior wall and the foundation still in place. The victim was transferred to the hospital, and on the way, he admitted to undoing the natural gas fitting and to igniting the source. He survived for a short interval of time in the hospital before all resuscitative efforts failed. During autopsy, a special attention was paid to victim's identification and search for other injuries, not related to the explosion, so as to exclude or document homicidal injuries disguised by the subsequent explosion. The forensic pathologist should be aware of the different kinds of inflammable substances and integrate the findings with the scene information and the impression of the investigators at the scene.     

Medical device reporting--FDA. Final rule

The Food and Drug Administration (FDA) is issuing a final rule that requires manufacturers and importers of medical devices, including diagnostic devices, to report to FDA whenever the manufacturer or importer receives or otherwise becomes aware of information that reasonably suggests that one of its marketed devices (1) may have caused or contributed to a death or serious injury or (2) has malfunctioned and that the device or any other device marketed by the manufacturer or importer would be likely to cause or contribute to a death or serious injury if the malfunction were to recur. FDA is taking this action under the Medical Device Amendments of 1976. The final rule is intended to assure that FDA is informed promptly of all serious problems or potentially serious problems associated with marketed devices. FDA is the principal public health agency responsible for ensuring that devices are safe and effective. To carry out its responsibilities, the agency needs to be informed whenever a manufacturer or importer receives or otherwise becomes aware of information about device problems. Only if FDA is provided with such information will it be able to evaluate the risk, if any, associated with a device and take whatever action is necessary to reduce or eliminate the public's exposure to this risk. Depending on the facts and circumstances, these steps could include contacting the manufacturer or importer of the device and monitoring its voluntary actions to respond to the problem, initiating a consumer or user education program, or initiating regulatory action, such as injunction, seizure, or other enforcement action.     

The use of orthopedic surgical devices for forensic identification

Surgically implanted devices have become increasingly common in modern skeletal material. Therefore, having the knowledge of the variety of implanted orthopedic devices, their manufacturer, and where to find and how to use identifying numbers in such implants can assist in the identification process when traditional methods are not applicable. Orthopedic device manufacturers are required by the Safe Medical Devices Act of 1990 and the FDA Modernization Act of 1997 to track permanently implanted devices. Manufacturer information on orthopedic devices associates the orthopedic surgeon who implanted the device with the patient. By providing a current list of the most common orthopedic device manufacturers in the U.S.A. and the associated contact information, investigators will have updated tools for the individuation process. Despite numerous complicating factors regarding how device data are tracked, the information presented here can assist forensic professionals with obtaining presumptive and/or positive identifications.     

Atomic force microscopic investigation of commercial pressure sensitive adhesives for forensic analysis

Pressure sensitive adhesive (PSA), such as those used in packaging and adhesive tapes, are very often encountered in forensic investigations. In criminal activities, packaging tapes may be used for sealing packets containing drugs, explosive devices, or questioned documents, while adhesive and electrical tapes are used occasionally in kidnapping cases. In this work, the potential of using atomic force microscopy (AFM) in both imaging and force mapping (FM) modes to derive additional analytical information from PSAs is demonstrated. AFM has been used to illustrate differences in the ultrastructural and nanomechanical properties of three visually distinguishable commercial PSAs to first test the feasibility of using this technique. Subsequently, AFM was used to detect nanoscopic differences between three visually indistinguishable PSAs.