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Story highlights

No conclusions drawn about cause of death pending additional review, coroner's office says

Otto Warmbier died days after he was returned to United States from North Korea

(CNN) —  

The family of American college student Otto Warmbier objected to an autopsy, leaving the former North Korea detainee’s official cause of death a mystery for the time being.

The Hamilton County Coroner’s Office in Ohio confirmed that it received and examined the 22-year-old’s body after his death on Monday.

The Warmbier family’s “objection to an autopsy was honored,” the office said, and only an external examination was performed.

The coroner’s office reviewed medical records from the University of Cincinnati Medical Center and the air ambulance service that helped bring Warmbier from Pyongyang to Cincinnati after 17 months. “Extensive” conversations with his treating physician took place, too.

“No conclusions about the cause and manner of Mr. Warmbier’s death have been drawn at this time as there are additional medical records and imaging to review and people to interview,” the statement said.

His death led to strong condemnations of the regime and speculation about the implications. Politicians renewed calls for the regime to release three US citizens being held in the country.

RELATED: The tour company that took Otto Warmbier to North Korea halts trips for Americans

Warmbier visited North Korea in January 2016 on a sightseeing tour. He was arrested for allegedly stealing a political sign from a restricted area and sentenced to 15 years of hard labor.

US President Donald Trump’s administration worked to secure his return. He died less than a week after returning from North Korea. He could not speak or move voluntarily and his doctors said he suffered extensive brain damage.

His treating physicians said he suffered from unresponsive wakefulness, a condition also known as persistent vegetative state. In a news conference before Warmbier’s death, they said they could not speculate on the cause of his condition. But they found no evidence that he had contracted botulism, casting doubt on North Korea’s claim that he fell into a coma after contracting botulism and taking a sleeping pill.

“This pattern of brain injury is usually seen as result of cardiopulmonary arrest where blood supply to the brain is inadequate for a period of time, resulting in the death of brain tissue,” Dr. Daniel Kanter said last week.

A funeral will be held Thursday at Warmbier’s alma mater, Wyoming High School in Ohio.

CNN’s Kelly Christ contributed to this report.