Honolulu's medical examiner says a Hawaii crime boss who died in federal detention this month was killed by an opioid overdose.

Michael Miske died of "toxicity of fentanyl and para-fluorofentanyl," the medical examiner’s office said in a statement obtained by AP. The death appears to have been accidental.

A medical examiner revealed a Hawaii crime boss died of an opioid overdose while in federal detention. Michael Miske, 50, was found unresponsive at the facility on December 1. It was later revealed that he died from "toxicity of fentanyl and para-fluorofentanyl,

The traveler has not been identified, but the airlines confirmed the person was discovered during the taxi out at Seattle-Tacoma International Airport Tuesday.

A passenger has been taken into custody for boarding a Delta flight to Hawaii without a boarding pass. It comes a month after another stowaway was discovered on a Delta flight to Paris. NBC’s Morgan Chesky reports for TODAY.

A Delta Airlines flight from Seattle to Honolulu was delayed by two hours after an unticketed passenger was discovered onboard.