Homicide Manner-of-Death Classification in Arrest-Related Death.

ABSTRACT: Multiple studies have documented various factors that influence or determine forensic pathologist classification of manner of death. There do not appear to be any published studies on manner of death classification specifically regarding arrest-related deaths (ARDs). The goal of this study was to consider a large body of cases of nonfirearm ARDs to analyze the homicide classification with regards to numerous decedent and practitioner (medical examiner/coroner [ME/C]) variables. We analyzed 1145 US autopsy reports from the years 2006-2020, inclusive, and considered decedent variables of age, ethnicity, height, weight, body mass index, toxicology, and mention of a conducted electrical weapon and ME/C influence variables of gender, country region, and year. We found that the homicide classification likelihood increased by a factor of 1.04-1.05 per year, 1.34-1.37 for a female medical examiner, and 1.4-1.5 going from Southern states to Western states. There is an increasing trend for ME/C to label nonfirearm ARDs as homicides in the United States. The homicide classification is more common in Western states and less common in Southern states, and it was more common with a female ME/C.

Do Saliva-Saturated Spit Hoods Interfere With Ventilation?

ABSTRACT: Spit hoods are used by law enforcement, officers in correctional facilities, and medical personnel during the restraint of agitated subjects that are actively spitting to prevent the transmission of droplet-transmitted pathogens. We could find no studies reporting on the time course of normal breathing to clear saliva from such a saturated spit hood. We purchased samples of 3 popular spit hood models and applied a section over the output of a pneumatic test system. We used a digital anemometer, digital manometer, and an inline controllable fan for back pressure and flow. The pressure was 3 mm Hg to match quiet breathing. The tested area was saturated with artificial saliva, and air pressure was applied while we recorded the pressure and airflow. Within 5 seconds, the spit hoods all cleared sufficient artificial saliva to allow 1 m/s of airflow, which exceeds that of an N95 mask with similar pressure. Commonly used spit hoods offer very low resistance to breathing even after being initially saturated with artificial saliva. Our results do not support the hypothesis that a saliva-filled spit hood might contribute to death.

The electrophysiology of electrocution.

Electrocution is a death caused by an application of electrical current to the human body. Our present understanding of electrocution-as the induction of ventricular fibrillation (VF)-followed a nearly century-long path of misunderstandings and speculation primarily focused on hypotheses of asphyxia as well as central nervous system trauma. It is hard for us today to appreciate the past mystery of an unexpected sudden death usually bereft of visible trauma. Even today, a false dogma exists that direct-current shocks can cause asystole instead of VF. A lightning discharge (up to 500 megavolts) is differentiated because it can cause substantial acute and chronic neural effects leading to other cardiac arrest rhythms. The human heart is exquisitely sensitive to alternating currents, and VF can be induced with currents of one-eighth that required for mere pacing. Because of these low currents, this effect obtains only in the TQ interval, and low-power electrocution does not involve the vulnerable period. If a current is strong enough to electrocute, generally it will do so in 1-2 seconds; longer shocks do not tend to be more dangerous. Regardless of concomitant drug dosing, the electrocution cardiac arrest rhythm is still VF, suggesting that electrocution is a stand-alone cause of death; the electrical current does not potentiate the effects of the drug. The experimental and clinical data supporting VF as the mechanism for electrocution are provided.

Electrocution Risk of Capacitive Discharge Shocks: Application to Electric Vehicle Charging.

It is difficult to electrocute (induce ventricular fibrillation) with capacitive discharge shocks. With small capacitance values, the high voltages required for the necessary charge are rarely seen in industrial situations (e.g. electric vehicle charging stations). On the other hand, with large capacitance values, the discharge time is so great that the shock couples inefficiently with the cardiac cells. The update to IEC 60479-2 sets the C1 "mostly-safe" charge limit of 3 mC for a short "impulse function" pulse. We calculated the equivalent capacitor stored charge for an arbitrary capacitance value using the simple single membrane time constant model for the cardiac response. The peak membrane response was set equal to that of the 3 mC impulse function response to calculate the safe values for stored charge, voltage, and energy. The total stored charge, per se, cannot be used simplistically to estimate the danger of a capacitive discharge shock. A capacitive-discharge shock cannot be accurately compared to a rectangular shock with a duration equal to the shock time constant. The greater the capacitance, the larger the fraction of wasted charge in coupling to the heart and thus the shorter equivalent duration compared to the shock time constant. For a capacitive discharge shock this translates to a stored charge of 3 mC increasing up to 9 mC for a 10 capacitor using the assumed 575 load for an electric-vehicle (EV) charging station. In the area of interest for 1 - 10 the safe voltage ranges from 1300 to 4700 V, which includes the 1500-VDCscope of EV charger standard IEC 61851-23. For C > 100 the voltage asymptote is 700 V.

Confusion between firearms and electrical weapons as a factor in police shootings.

Conducted electrical weapons (CEW) have risks including trauma associated with uncontrolled falls, probes penetrating the eye, and fume ignition. A lesser-known risk is weapon-confusion error with officers mistakenly discharging their firearm when they intended to deploy their electrical weapon. We searched for incidents of possible weapon confusion with the TASER® brand CEWs via open-source media, litigation filings, and a survey of CEW law enforcement master instructors. We found 19 incidents of possible CEW weapon confusion in law enforcement field uses from January 2001 to April 2021. We eliminated a case as not meeting our criteria for probable weapons confusion leaving 18 cases, thus giving a demonstrated CEW discharge risk of 3.9 per million with confidence limits (2.4-6.2 per million) by Wilson score interval. Ipsilateral carry of the weapons was historically correlated with increased risk vs. contralateral carry. Officer gender was not a predictor of weapon confusion. The psychological issues behind weapon confusion under stress are discussed. The concurrent carry of electrical weapons and firearms presents a very small but real risk of injury and death from confusion between an electrical weapon and a firearm.

Pneumatic Impedance of Spit Socks and N95 Masks: The Applicability to Death Investigation.

INTRODUCTION: Restrained subjects often spit on law enforcement and corrections officers and medical responders. Based on the droplet-transmitted risk of COVID-19, such spitting could be considered a potentially life-threatening assault. Officers commonly use "spit socks" over the head and neck of spitting subjects to reduce this risk. The pneumatic impedance of such socks has not been published, so this remains an open issue for arrest-related death investigation. METHODS: We purchased samples of 3 popular spit sock models, 3 insect-protecting "bug" socks and hats, 3 N95 masks, a standard 3-ply surgical mask, and a common dust mask. We used a BTmeter model BTN8468 digital anemometer, an HTI model HT-1890 digital manometer, and an AC Infinity Cloudline model S6 inline controllable fan to measure air flow versus pressure drop. We compared the curves graphically and also calculated a pneumatic pseudo-impedance by dividing the pressure drop by the air velocity. RESULTS: The spit and bug socks allowed nearly maximum airflow with minimal pressure (≤1 mm Hg), whereas none of the masks allowed greater than 2 m/s of airflow at maximum pressure of 3 mm Hg. All of the spit and bug masks were grouped together with the lowest pneumatic impedances, whereas all of the N95 masks were grouped together with the highest values. The dust mask and surgical mask were in between with the dust mask closer to the spit and bug masks, whereas the surgical mask was closer to the N95 masks in impedance. CONCLUSIONS: Commonly used spit socks offer nearly zero resistance to breathing. The highest resistance spit sock was still 100 times better than the best N95 mask for airflow during inhalation. Our results do not support the occasional hypothesis that spit socks might contribute to an arrest-related death.

Estimation of Physiological Impedance from Neuromuscular Pulse Data.

INTRODUCTION: A Conducted Electrical Weapon (CEW) deploys 2, or more, probes to conduct current via the body to induce motor-nerve mediated muscle contractions, but the inter-probe resistances can vary and this can affect charge delivery. For this reason, newer generation CEWs such as the TASER® X3, X2 and X26P models have feed-forward control circuits to keep the delivered charge constant regardless of impedance. Our main goal was to explore the load limits for this "charge metering" system. A secondary goal was to evaluate the reliability of the "Pulse Log" stored data to estimate the load resistance. METHODS: We tested 10 units each of the X2 (double shot), X26P, and X26P+ (single-shot) CEW models. We used non-inductive high-voltage resistor assemblies of 50, 200, 400, 600, 1k, 2.5k, 3.5k, 5k, and 10k Ω, a shorted output (nominal 0 Ω), and arcing open-circuits. The Pulse Log data were downloaded to provide the charge value and stimulation and arc voltages for each of the pulses in a 5 s standard discharge cycle. RESULTS: The average reported raw charge was 65.4 ± 0.2 µC for load resistances < 1 kΩ consistent with specifications for the operation of the feed-forward design. At load resistances ≥ 1 kΩ, the raw charge decreased with increasing load values. Analyses of the Pulse Logs, using a 2-piece multiple regression model, were used to predict all resistances. For the resistance range of 0 - 1 kΩ the average error was 53 Ω; for 1 kΩ - 10 kΩ it was 16%. Muzzle arcing can be detected with a model combining parameter variability and arcing voltage. CONCLUSIONS: The X2, X26P, and X26P+ electrical weapons deliver an average charge of 65 µC with a load resistance < 1 kΩ. For loads ≥ 1 kΩ, the metered charge decreased with increasing loads. The stored pulse-log data for the delivered charge and arc voltage allowed for methodologically-reliable forensic analysis of the load resistance with useful accuracy.

Detection of Arcing and High Impedance with Electrical Weapons.

INTRODUCTION: Conducted electrical weapons are primarily designed to stop subjects from endangering themselves or others by deploying 2, or more, probes to conduct current via the body to induce motor-nerve mediated muscle contractions, but probe impedance can vary significantly including open circuits from probes failing to complete or maintain a circuit. METHODS: We tested 10 units of the TASER® 7 model with a range of impedances and open circuit conditions. Pulse data (stored in the device's memory) were used to predict the load resistances and detect arcing conditions. Acoustical data (recorded externally) was evaluated on an exploratory basis as a secondary goal. RESULTS: The average error of predicted resistance, over the physiological load range of 400-1000 Ω, was 8%. Arcing conditions was predicted with an accuracy of 97%. An arcing condition increases the duration of the sound generation. CONCLUSIONS: The TASER 7 electronic control device stored pulse-log data for charge and arc voltage yielded forensic analysis of the load resistance with reliable accuracy.

Ventricular Fibrillation Threshold vs Alternating Current Shock Duration.

INTRODUCTION: International basic safety limits for utility-frequency electrical currents have long been set by the International Electrotechnical Commission 60479-1 standard. These were inspired by a linear-section plot proposed by Biegelmeier in 1980 with current given as a function of the shock duration. This famous plot has contributed to safe electrical circuit design internationally and has properly earned significant amount of respect over its 35 years of life. However, some possible areas for improvement have been suggested. METHODS: We searched for all animal studies of ventricular fibrillation threshold versus duration that used a forelimb to hindlimb connection that had at least 3 durations tested. We found 6 such studies and they were then used to calculate a new C3 curve after normalizing the data. RESULTS: A rational function model fit the animal data with r2 = .96. Such a correlation calculation tends to underweight the smaller values, so we also correlated the log threshold values and this had a correlation of r2=.94. CONCLUSION: Existing ventricular fibrillation threshold current versus duration data can be fitted with a simple rational function. This can provide a useful update to IEC 60479-1.

Output of Electronic Muscle Stimulators: Physical Therapy and Police Models Compared.

INTRODUCTION: Both physical therapists and police officers use electrical muscle stimulation. The typical physical therapist unit is attached with adhesive patches while the police models use needle-based electrodes to penetrate clothing. There have been very few papers describing the outputs of these physical therapy EMS (electrical muscle stimulator) units. METHODS: We purchased 6 TENS/EMS units at retail and tested them with loads of 500 Ω, 2 kΩ, and 10 kΩ. RESULTS: For the typical impedance of 500 Ω, the EMS units delivered the most current followed by the electrical weapons; TENS units delivered the least current. At higher im-pedances (> 2 kΩ) the electrical weapons delivered more current than the EMS units, which is explained by the higher voltage-compliance of their circuits. Some multi channel EMS units deliver more calculated muscle stimula tion than the multi-channel weapons. CONCLUSION: Present therapeutic electrical muscle stimula-tors can deliver more current than present law-enforcement muscle stimulators.

Humidity and Ventricular Fibrillation: When Wet Welding can be Fatal.

INTRODUCTION: Arc welding is generally considered very safe electrically. There have been electrocution cases with welders in high humidity environments. When dry, the flux coatings tend to have sufficient electrical resistance to limit the current below that required for the induction of VF (ventricular fibrillation). METHODS: We tested 4 welding electrodes for resistance in both dry and wet conditions. To estimate the cardiac current density - in a worst-case scenario - we used a 20k element finite-element bioimpedance model with 1 cm of skin and fat along with 1 cm of muscle before the heart of 5 cm dimensions. Between the heart and a metal plate we assumed 5 cm of lung and 1 cm of skin and fat. RESULTS: Welding electrode flux is highly resistive when dry. However, when saturated with moisture the resistance is almost negligible as far as dangerous currents in a human. The FEM model calculated a current density of > 7 mA/cm2 on the ventricular epicardium with a source of 80 V at the welding rod. CONCLUSION: In conditions of high humidity, a supine operator, in contact with a coated welding electrode to the precordial region of the body can be fibrillated with the AC open-circuit voltage. Most reported DC fatalities were probably due to pseudo-DC outputs that were merely rectified AC without smoothing.

Police shootings after electrical weapon seizure: homicide or suicide-by-cop.

PURPOSE: Risks of handheld electrical weapons include head impact trauma associated with uncontrolled falls, ocular probe penetration injuries, thermal injuries from the ignition of volatile fumes, and weapon confusion police-involved shooting. There is also an uncommon but critical risk of a shooting after a subject gained control of an officer's electrical weapons. METHODS: The authors searched for police shooting incidents involving loss of control of TASER® weapons via open-source media reports, crowd-sourced internet sites, litigation filings, and a survey of Axon law-enforcement master instructors. RESULTS: The authors report 131 incidents of subjects attempting to or gaining control of an officer's electrical weapon from 2004 to 2020, 53 of which resulting in a shooting. These incidents demonstrated a risk of 11.8 shootings per million electrical weapon discharges (95% confidence limits of 9.0 to 15.1 per million by Wilson score interval). CONCLUSIONS: The use of electrical weapons presents a rare but real risk of injury and death from a shooting following a subject's attempts to gain control of the weapon.

Electrical weapons and rhabdomyolysis.

It has been suggested that an application of a conducted electrical weapon (CEW) might cause muscle injury such as rhabdomyolysis and an acute inflammatory response. We explored this hypothesis by testing the effects of electrical weapons on circulating markers of inflammation and muscle damage. In a prospective study, 29 volunteers received a full-trunk 5-s TASER® X26(E) CEW exposure. Venous blood samples were taken before, 5 min after, and at 24 h following the discharge. We tested for changes in serum levels of C-reactive protein (CRP), alkaline phosphatase (ALP), myoglobin, albumin, globulin, albumin/globulin ratio, aspartate and alanine aminotransferase, creatine kinase, total protein, bilirubin, and lactic acid dehydrogenase. Uncorrected CRP and myoglobin levels were lower in the immediate post exposure period (CRP levels 1.44 ± 1.39 v 1.43 ± 1.32 mg/L; p = 0.046 and myoglobin 36.8 ± 11.9 v 36.1 ± 13.9 µg/L; p = 0.0019) but these changes were not significant after correction for multiple comparisons. There were no changes in other biomarkers. At 24 h, CRP levels had decreased by 30% to 1.01 ± 0.80 mg/L (p = 0.001 from baseline). ALP was unchanged immediately after the CEW application but was reduced by 5% from baseline (66.2 ± 16.1 to 62.7 ± 16.1 IU/L; p = 0.0003) at 24 h. No other biomarkers were different from baseline at 24 h. A full-trunk electrical weapon exposure did not lead to clinically significant changes in the acute phase protein levels or changes in measures of muscle cellular injury. We found no biomarker evidence of rhabdomyolysis.

Computational models for contact current dosimetry at frequencies below 1 MHz.

Electric contact currents (CC) can cause muscle contractions, burns, or ventricular fibrillation which may result in life-threatening situations. In vivo studies with CC are rare due to potentially hazardous effects for participants. Cadaver studies are limited to the range of tissue's electrical properties and the utilized probes' size, relative position, and sensitivity. Thus, the general safety standards for protection against CC depend on a limited scientific basis. The aim of this study was therefore to develop an extendable and adaptable validated numerical body model for computational CC dosimetry for frequencies between DC and 1 MHz. Applying the developed model for calculations of the IEC heart current factors (HCF) revealed that in the case of transversal CCs, HCFs are frequency dependent, while for longitudinal CCs, the HCFs seem to be unaffected by frequency. HCFs for current paths from chest or back to hand appear to be underestimated by the International Electrotechnical Commission (IEC 60479-1). Unlike the HCFs provided in IEC 60479-1 for longitudinal current paths, our work predicts the HCFs equal 1.0, possibly due to a previously unappreciated current flow through the blood vessels. However, our results must be investigated by further research in order to make a definitive statement. Contact currents of frequencies from DC up to 100 kHz were conducted through the numerical body model Duke by seven contact electrodes on longitudinal and transversal paths. The resulting induced electric field and current enable the evaluation of the body impedance and the heart current factors for each frequency and current path.

Safety of a High-Efficiency Electrical Fence Energizer.

INTRODUCTION: Our primary goal was to evaluate the performance of a new high-efficiency electric fence energizer unit using resistive load changes. Our secondary goal was to test for compliance with the classical energy limits and the newer charge-based limits for output. METHODS: We tested 4 units of the Nemtek Druid energizer with 2 channels each. We used a wide load-resistance range to cover the worst-case scenario of a barefoot child making a chest contact (400 Ω) up to an adult merely touching the fence (2 kΩ). RESULTS: The energy output was quite consistent between the 8 sources. Even at the lowest resistance, 400 Ω, the outputs were well below the IEC 60335-2-76 limit of 5 J/pulse. The charge delivered was also quite consistent. Even at the lowest resistance, 400 Ω, the outputs (679 ± 23 µC) were well below the proposed limits of 4 mC for short pulses. CONCLUSIONS: The high-efficiency electric fence energizers satisfied all relevant safety limits. Charge, energy, voltage, and current outputs were consistent between channels and units.

Electrical weapons, hematocytes, and ischemic cardiovascular accidents.

BACKGROUND: There have been case reports following the use of a conducted electrical weapon (CEW) suggesting that these devices might affect coagulation or thrombosis in at-risk individuals. The aim of this manuscript therefore is firstly to explore this hypothesis by reviewing each of these cases and secondly to report the results of a prospective study exploring a priori the effects of electrical weapons on hematocytes in a group of human volunteers. METHODS: First, we systematically reviewed all cases of adverse outcomes following CEW discharge that could be due to an effect on coagulation or thrombosis, with particular focus on the clinical scenario and its relationship with the weapon discharge. Second, we assessed hematocyte levels in venous blood from 29 volunteers before, 5 min after, and 24 h after receiving a full-trunk 5-s TASER® X26(E) CEW exposure. RESULTS: Following extensive review of the literature, we found 3 relevant case reports of possible vascular thromboembolic clinical events after CEW exposure, specifically a case of ischemic stroke, and 2 cases of ST-segment elevation myocardial infarctions. Review of these published cases failed to establish a plausible linkage to the CEW beyond a temporal association with significant emotional and physiological stress from a violent struggle. Our prospective study of biomarker change following CEW discharge revealed acutely increased values for WBC (white blood cells), specifically lymphocytes and monocytes, and a raised platelet count. Neutrophil levels decreased as a percentage of WBC. While these changes were statistically significant at 5 min, all results remained within established reference ranges. At 24 h, all values had returned to baseline except total WBC which decreased to slightly below baseline but was still within the normal reference range. CONCLUSIONS: A review of clinical cases, of ischemic or thrombotic events revealed no direct association with the CEW discharge. A full-trunk electrical weapon exposure did not lead to hematocyte changes beyond normal clinically expected variations in similar acute response scenarios. The case report and biomarker data do not support the hypothesis that a CEW discharge is associated with changes likely to promote coagulation or thrombus formation.

Impedance in the Diagnosis of Lead Malfunction.

Impedance is the ratio of voltage to current in an electrical circuit. Cardiovascular implantable electronic devices measure impedance to assess the structural integrity electrical performance of leads, typically using subthreshold pulses. We review determinants of impedance, how it is measured, variation in clinically measured pacing and high-voltage impedance and impedance trends as a diagnostic for lead failure and lead-device connection problems. We consider the differential diagnosis of abnormal impedance and the approach to the challenging problem of a single, abnormal impedance measurement. Present impedance provides a specific but insensitive diagnostic. For pacing circuits, we review the complementary roles of impedance and more sensitive oversensing diagnostics. Shock circuits lack a sensitive diagnostic. This deficiency is particularly important for insulation breaches, which may go undetected and present with short circuits during therapeutic shocks. We consider new methods for measuring impedance that may increase sensitivity for insulation breaches.