South Korea's forensic agency said on Friday it was impossible to determine the cause of death of a businessman linked to a ferry that sank and killed 304 people in April, deepening the mystery surrounding the final days of Korea's most wanted man.
An autopsy and DNA tests on the badly decomposed body of Yoo Byung-un revealed no evidence that he was poisoned, and there was also no indication of external trauma, forensic agency chief Seo Joong-seok told a news conference.
Yoo, 73, was found dead in an orchard on June 12 after eluding authorities for nearly two months in South Korea's biggest manhunt, hiding behind the wall of a rural cabin in the final days while it was being searched.
Police identified his body only this week, 40 days after a farmer reported its discovery at his orchard, stirring a storm of public outrage at what many said was incompetent work to arrest Yoo over the ferry disaster.
"We are aware there are many questions and did our best, but it was impossible to determine the cause of death," said Lee Han-young, a senior official at the forensic agency.
"It is possible in some cases involving decomposed bodies to determine the cause of death but, in Yoo Byung-un's case, there was simply too much tissue damage so it was difficult to find leads that can determine the cause of death," he said.
The autopsy found no evidence of trauma from a weapon or strangulation, although there was heavy decomposition damage to the tissues in the head and neck, Lee said.
Kang Shin-mong, a forensic expert at the Catholic University of Korea's School of Medicine, said after the agency's announcement it was possible Yoo died of hypothermia, citing his age and a history of diabetes.
Weather records showed temperatures in the region where his body was found dipped to 12 degrees Celsius (54 degrees Fahrenheit) at night in late May and early June.
Yoo headed the family that owned the operator of the ferry, Sewol, which capsized and sank on April 16 on a routine journey. Many of those killed were children from the same school on a class trip.
The ferry disaster triggered outrage across South Korea, especially when video footage emerged of crew members abandoning ship while the children stayed in their cabins as instructed.
The Sewol's 15 surviving crew members, including the captain, are on trial on charges ranging from negligence to homicide.
Yoo was wanted on charges of embezzlement, negligence and tax evasion but managed to elude authorities in what became a political headache for President Park Geun-hye, whose government came under heavy criticism for its handling of the disaster.
The failure by the national forensic agency to determine how Yoo may have died, and how his body arrived at the spot where it was found, is likely to add pressure on authorities to arrest two close associates accused of aiding his flight.
The older of his two sons, who co-owned the holding company at the center of a network of business interests that included the ferry operator, remains at large. The younger son is believed to be in the United States.
A senior prosecutor who headed the investigation resigned on Thursday, claiming responsibility for botched moves that allowed Yoo to remain at large for so long.
Three police officers, including the provincial chief of the region where his body was found, were sacked this week.