In December, in a house in Port St. Lucie, Florida, Joseph Overholt died alone in the room hed been renting. He was 28. It would be days before another tenant discovered his body laid out on a bed in the early stages of decomposition.

There was no obvious cause of death. Overholt was obese, and a medical examiner determined he had excess fluid in his lungs, a condition frequently seen in cases of drug overdose or heart failure. Nothing else appeared remarkable.

Toxicology results would offer an easier answer. The report showed the presence of alcohol, caffeine and the prescription antidepressant citalopram all fairly common. The final substance listed was mitragynine, a psychoactive alkaloid in the popular herbal supplement kratom that is naturally responsible for some of the plants opioid-like effects. A screen for fentanyl, a synthetic opioid many times more powerful than heroin, would come back inconclusive due to interfering substance(s) present in specimen.

Five unknown brown pills were in Overholts bathroom, according to a police officer at the scene. That description would be consistent with a kratom product, but the medical examiner did not respond to questions about whether his office had the pills tested, or whether he could say for certain that Overholt had taken any of the pills before his death.

In January, more than 45 days after Overholts death, an assistant medical examiner concluded that hed overdosed on kratom . The cause of death: mitragynine toxicity.