What is kratom, the 'gas station heroin' alarming officials in the US?
Kratom, found during an investigation into the deaths of two college students, has been sold in the US for around a decade.
Jeffrey Deaver, a 58-year-old retired timber cutter in the state of Washington, has taken kratom for four years to help with severe chronic hip and knee pain.
He discovered the herbal product when he couldn't find relief from doctors and while waiting for surgeries. Scared at first, he "started small", but then took more until his pain went away.
Kratom - an herb with opioid-like effects - has grown in popularity in the US over the last decade, and is typically purchased over-the-counter and consumed in pill or liquid form.
"It's almost like taking a narcotic," Speights said. "At higher doses, it can create more euphoria and give you more of a general high."