KUALA LUMPUR (THE STAR/ASIA NEWS NETWORK) - For more than a year, everyone had been made to believe that the deaths of six people at the Future Music Festival Asia (FMFA) 2014 were due to drug overdose.

But post-mortem results issued two months after the deaths showed the cause to be heatstroke, with drugs playing a negligible role.

Two out of the 16 revellers brought to hospital in critical condition did not even have any trace of illegal substance, according to a pathologist involved in the case, contradicting police statements that all the deaths were linked to drugs.

Yet, the authorities did not make the results known and the "drug overdose deaths" was used as grounds to cancel several concerts here recently and one in Singapore.

University Malaya Medical Centre (UMMC) forensic pathology department head Prof Dr K. Nadesan said he had sent several detailed reports correcting the police statements.

"Generally, the police did not show much interest in the reports. Unfortunately, they made statements without proper scientific reasons, which is not the right way.

"They should have spoken to us and encouraged an inquest into the case because it is a matter of public interest to prevent similar incidents," he told The Star.

Dr Nadesan said the hospital handled the post-mortem for three of the dead and also treated nine others.

He said those who died tested positive for ecstasy or MDMA, but it was much lower than the average recreational level of 0.1 to 0.25 microgram per millilitre.

The six, who died after the concert at the Bukit Jalil Stadium on March 15 last year were Kamal Zekry Kamal Basha, 22; Victor Wong E Hern, 26; Sabreena Kamaruddin, 21; M. Suresh, 28; Syazana Sohaime, 23; and Nor Faizza Mohd Wazir, 27.

Autopsies on the "virtually dried up" bodies, including one which had a temperature of 39°C, led Dr Nadesan to rule the deaths as caused by heatstroke.

"I was surprised because when I came in, the impression created from the police announcement was that they had taken large doses of drugs.

"Even the clinicians at the trauma centre were under the impression that these people were heavily intoxicated with drugs and were treating them for overdose instead of heatstroke.

"The autopsy and clinical findings were not on par with drug overdose. The police had no grounds to say it was. It was a wrong assumption," he said.

Dr Nadesan said two of the nine heatstroke victims had no traces of drugs in their system while the rest tested positive for MDMA, ketamine and morphine.

Universiti Kebangsaan Malaysia Hospital (HUKM), which handled the autopsies for three other victims, declined to reveal the results.

KL Criminal Investigation Department chief Senior Asst Comm Datuk Zainuddin Ahmad confirmed that the sudden death reports for the six had listed heatstroke as the cause.

Dr Nadesan said the conditions during the second day of the festival - a combination of choking haze, high humidity and 35°C temperature - were the main causes of the tragedy.

He said the stadium where they were from 10am to 1am, without sufficient fluids and dancing for hours, provided the conditions for heatstroke.

Dr Nadesan said some of the victims, especially those who taken MDMA, became uninhibited and overexerted themselves physically, causing their bodies to lose control in regulating temperatures.

The victims stopped sweating while their bodies experienced disseminated intravascular coagulopathy (DIVC) which causes internal haemorrhaging, blood clotting and lower oxygen delivery to organs.

"This led to multiple organ failures, a shutdown of the body," he said.

Dr Nadesan said the drugs might have in some small way contributed to the deaths but they were not the main cause.

He felt the tragedy could have been averted had the organisers provided adequate access to water and information on how to stay healthy in the harsh weather.

Even after a year, the tragedy hung like a spectre over the Malaysian nightlife and concert scene.

The alleged drug overdose were cited as the reason for the cancellation of several concerts, including the Life In Colour in April 2014 and Thirst 2015: We Are All Stardust in April.

In March, Singapore cancelled a concert to be held at the Changi Exhibition Centre "because of serious concerns over drug abuse".