A 22-year-old man died after taking an "unknown substance" at the event.
Police are appealing for assistance as they continue to investigate the death of a 22-year-old man at Lost Paradise festival late last year.
Brisbane local Joshua Tam died at the Gosford event on 29 December after taking an "unknown substance". After falling unconscious and being treated by medical staff at the venue, Tam was transported to Gosford Hospital where he later died.
Police are asking anyone who was with Tam before or during the festival to step forward. In particular, they are seeking assistance from a woman who was with Tam when medical staff first responded to his collapse.
The woman is believed to be an acquaintance of Tam and spoke briefly to the medical team, however she left without giving her details.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or through this link.
The Coroners Court has confirmed it will hold a public hearing into the recent suspected-drug-overdose-deaths at music festivals over the last six months, including Tam and 19-year-old Alex Ross-King who died after attending FOMO Festival in Sydney last weekend.
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Meanwhile on Friday, Australia's peak body for physicians, the Royal Australasian College of Physicians, called on state premiers to introduce pill testing at Australian music festivals in an open letter.
"In light of the six deaths at festivals in Australia since last September, we urge you to follow the lead of the ACT government in consulting with medical experts to establish pill testing trials in your state or territory,” the letter reads.
The NSW government has also been urged to launch a "pilot pill testing trial" at Ultra Music Festival Australia in Sydney next month.