Passenger, 22, who died on Southwest flight was killed by new drug 7-OH as medical examiner gives update

The cause of death has been revealed for the passenger who tragically passed away during a domestic flight earlier this year.

Rain McMillen Walmsley was just 22 years old when he suffered a fatal medical emergency while traveling with Southwest Airlines from Dallas to Los Angeles on August 7.

Los Angeles County Medical Examiner has now closed the investigation into his death, with the coroner ruling his death as an accident caused by the combined effects of two specific chemical compounds.

The autopsy report cited 7-Hydroxymitragynine and Mitragynine, which are more commonly referred to collectively as 7-OH.

Both of these drugs are derived directly from the kratom plant - a herbal tree that is native to regions across Southeast Asia.

The leaves of the plant are typically dried and consumed for their stimulant or sedative effects, and the substance remains federally unregulated - and because it is not a controlled substance, it can be legally purchased over the counter or online.

Rain McMillen Walmsley died after suffering a medical emergency on a Southwest Airlines flight in August (Heather McMillen)

It is frequently advertised to consumers as a mild stimulant similar to caffeine, while some brands market it as a natural anxiety reducer.

However, 7-OH is actually a highly concentrated product found within the plant that contains much higher levels of dangerous opioid-active alkaloids.

While occasionally marketed as a natural supplement, the American College of Medical Toxicology warns that these specific compounds function exactly like typical opioids.

Medical experts note that consuming these concentrated chemicals can lead to severe intoxication, respiratory depression, extreme dependence, and harsh withdrawal symptoms.

Walmsley suffered his fatal reaction while aboard Flight 958, reportedly experiencing a seizure in his seat before losing consciousness in the cabin.

Emergency paramedics were waiting on the tarmac at Los Angeles International Airport, but despite their best resuscitation efforts, he could not be saved.

Following the tragedy, his mom, Heather McMillen, spoke with local news outlets to pay tribute.

The substance, known as 7-OH, is a highly concentrated compound derived from the kratom plant that closely mimics the effects of opioids (Texas Department of State Health Services)

"He was a little spark plug, and he was beautiful and really smart and also really kind," she told Vashon-Maury Island Beachcomber. "He was just coming into himself."

"He was a beautiful soul."

Walmsley grew up on an island off the coast of Seattle before eventually moving across the country to study at Hunter College in New York.

He had graduated with a journalism degree just months before his death, and was traveling to California to visit his extended family.

The hidden dangers of kratom products recently came into the spotlight following the tragic deaths of two students at the University of Mississippi - Aidan Hamilton and Robert Strang both died in separate locations in Oxford after allegedly purchasing the substance from local vendors.

Police received separate reports that the young men were unresponsive, and toxicology reports later found mitragynine and potent opioid compounds in their systems.

Authorities discovered packaged supplements sold by a local retail store during both investigations, prompting discussions about banning the unregulated drug.

Two smoke shop employees who allegedly sold the products to the students were subsequently arrested for possession of a controlled substance with intent to distribute.