Cocaine on postmortem skin can reflect exposure, surface contamination or a combination. A 2026 study strengthened some exposure assessments by detecting networks of cocaine metabolites in skin extracts, including cases with negative conventional toxicology reports. It did not establish that any single skin metabolite conclusively excludes contamination or determines when cocaine was used.
The specimen and study setting
Wasinger and colleagues collected dermal extracts from 93 people during medicolegal autopsy. Water-wetted paper was pressed against fingers and soles for five minutes. Initial cases included a brief hand-rinsing comparison, while subsequent collections generally used unwashed hands and feet. Samples were frozen at −20°C for up to three months before dilute-and-shoot extraction and untargeted high-resolution LC–MS/MS analysis.
Exact death timing was unavailable for 35 people; known-time autopsies extended to 18 days after death. This was not a controlled cocaine administration experiment or a controlled environmental-contamination challenge. Its results must retain that casework context.
Why cocaine alone was not the decisive finding
Dermal analysis reported cocaine in 51 people, compared with six conventional toxicology reports. Benzoylecgonine was reported in 37 dermal assessments versus nine conventional reports. Those differences did not establish 45 missed cocaine users or 28 proven missed benzoylecgonine exposures.
The authors recognized that both cocaine and benzoylecgonine can occur through surface contamination. They therefore examined additional metabolites: ecgonine, hydroxybenzoylecgonine, norbenzoylecgonine and norcocaine, alongside ecgonine methyl ester and other available findings.
What the metabolite-network assessment added
In nine cases identified as cocaine consumption through conventional toxicology, dermal extracts contained at least four additional cocaine metabolites. Applying the expanded assessment to other dermal-positive cases identified eight further people with networks of four or more metabolites, resulting in 17 suspected cocaine consumers.
The eight additional people had died from other drug intoxications in six cases and polytrauma in two. Their other toxicology findings made cocaine exposure plausible, but those circumstances were corroborating context rather than independent proof of cocaine use.
Ecgonine methyl ester was consistently detected across sampled sites in all 17 suspected consumers. Hydroxybenzoylecgonine and norcocaine were robustly detected across matched sites in 15 of 17. Multiple chemically related findings and more than one anatomical sampling location gave a stronger basis for interpretation than an isolated parent-drug signal.
Alcohol-related markers had a narrower role
Twelve suspected cocaine consumers had ethanol reported in blood or urine by conventional testing. Eleven of those had both cocaethylene and ethyl glucuronide identified in dermal extracts. This supported the researchers’ co-exposure interpretation; it did not quantify the earlier blood ethanol concentration or establish a contribution to death.
The dermal LC–MS/MS method did not directly determine ethanol because of its mass-range constraints. A positive ethyl-glucuronide finding should not be rewritten as a measured ethanol concentration.
Why the study did not settle contamination in every case
The dermal results were qualitative. Candidate identification used exact mass, isotope patterns and MS/MS fragmentation, with authentic-standard verification for a subset of compounds. The study did not establish a validated environmental cutoff, metabolite-count threshold with known sensitivity and specificity, or a human dose-to-skin calibration.
The authors proposed that drugs may remain in skin longer than in conventional matrices. That explanation was plausible but not a controlled detection-window measurement. They also acknowledged possible effects of postmortem redistribution and decomposition and called for more data to distinguish exposure, contamination and postmortem change.
What a defensible interpretation preserves
Report the parent and metabolite identities, sampling sites, identification certainty and comparator findings. Describe the network as strengthening an exposure assessment rather than converting every discordance into a proven missed exposure. None of these qualitative findings measures impairment or establishes cocaine as a cause of death.
For another problem involving the source of a metabolite, see shared nitazene metabolites and parent-drug attribution.
Primary source
Wasinger D, Stolz K, Wolf M, et al. Analysis of postmortem dermal extracts is an efficient illicit drug screening method supporting forensic medicine. Scientific Reports. 2026;16:14183. doi:10.1038/s41598-026-45056-5.
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