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Formalin pigment deposition is a known artifact of autopsy histology, often anecdotally associated with decomposition of bodies. However, there is minimal data within the forensic literature demonstrating an association between formalin pigment deposition and length of postmortem interval. Furthermore, there is minimal data concerning other predisposing factors and patterns of distribution of formalin pigment deposition. In this study, we compare the amount and patterns of formalin deposition on histology slides from three categories of death: 1) decomposed bodies, 2) critically ill at time of death, and 3) sudden cardiac death. We also compare the effectiveness of two relatively simple histology laboratory methods to remove formalin pigment deposition from histology slides. Amongst the three categories of death, formalin deposition was highest in the decomposed category, second highest in the critically ill category, and lowest in the sudden cardiac death category. The organs most severely affected by formalin deposition were liver/spleen/pancreas and kidneys, and the organs least affected were brain and lung. Formalin pigment deposition correlated with length of postmortem interval. Histologic patterns of formalin deposition included the endothelial lining of vessels, perinuclear compartment of neurons and myocytes, and the basal epithelial compartment of renal tubular epithelial cells. The alcoholic ammonium hydroxide method (AAH) was slightly more effective than the alkylphenol ethoxylate (APE) method for removing formalin pigment, though both methods were effective. Because formalin pigment is strongly refractile under polarized light, a polarization filter can also be useful for distinguishing formalin pigment from other pigments.

Transdermal fentanyl, an opioid used for management of marked pain, also is abused and may cause death.We reviewed medical examiner reports of 92 decedents who had one or more fentanyl transdermal patches on their body and had fentanyl detected in their postmortem toxicology analysis.The manners of death included 40 accidents, 36 natural, 8 suicides, 5 therapeutic complications, and 3 undetermined deaths. Among the accidental fentanyl intoxication deaths, 32 of 37 involved substance abuse. The majority (95 %) of the 37 accidental deaths involving fentanyl were multi-drug intoxications. The substance abuse deaths had a mean fentanyl blood concentration (26.4 ng/ml or μg/L) that was over twice that of the natural group (11.8 ng/ml). Our analysis suggests a relationship between total patch dosage and mean postmortem fentanyl concentration up to the 100-μg/h dose.The very wide and overlapping ranges of postmortem fentanyl concentrations effectively nullify the utility of correlating the dose and expected postmortem concentration for any particular death. Based on the variable relationship between dose and blood concentration, the antemortem dose cannot be reliably predicted based on the postmortem concentration. This does not, however, render the medical examiner/coroner unable to determine the cause and manner of death because the toxicology results are only one datum point among several that are considered. Although there was a weakly positive relationship between body mass index and fentanyl concentration, further research is needed to determine whether adipose tissue represents a significant depot for postmortem release of fentanyl.