Oklahoma Forensic Study: Mitragynine Found in 28 Deaths, Minimal Postmortem Redistribution Aids Cause-of-Death Determination

Why it matters

As kratom use rises and increasingly appears in medical examiner casework, forensic pathologists and toxicologists lack standardized reference data for interpreting mitragynine concentrations at death — this Oklahoma study fills that gap with the largest single-state dataset yet published.

The big picture

Mitragynine's prevalence in forensic casework has grown alongside kratom's legal and commercial expansion. Unlike many drugs, mitragynine's postmortem redistribution behavior was largely unknown, making it difficult for coroners and medical examiners to accurately interpret toxicology results in death investigations. This study from Oklahoma examines 28 cases over two years to establish baseline forensic reference values.

Key findings

• 28 Oklahoma death investigation cases (2022–2023) included mitragynine quantification alongside demographics, pathology findings, and other toxicology results
• Postmortem heart blood mitragynine concentrations ranged from 130 to 2,600 ng/mL (mean 735 ng/mL; median 550 ng/mL)
• Femoral blood concentrations ranged from 130 to 7,500 ng/mL (mean 900 ng/mL; median 570 ng/mL)
• Mitragynine exhibits minimal postmortem redistribution overall (central-to-peripheral ratios mostly near 1.0), though individual cases showed variability
• 22 of 28 cases listed mitragynine in the cause of death; 21 of those also had at least one additional drug present
• Analysis was performed via LC/MS-MS following supported liquid extraction — a validated, reproducible method now detailed for peer laboratories

What they say

The authors concluded that 'the data presented shows the importance of quantifying mitragynine in medicolegal death investigations to aid in cause and manner of death determination' and note the limited postmortem redistribution makes interpretation more reliable than many other drugs.

Bottom line

This is the largest Oklahoma-specific forensic dataset for mitragynine: it shows the drug seldom kills alone (21 of 22 fatal cases involved other substances) and that postmortem redistribution is minimal — making accurate toxicology interpretation feasible for medical examiners.