The 25-year-old’s body was found in a wooded area on the edge of the festival site at Lulworth Castle in Dorset just before 1am on Monday.
Her parents – Holby City star John Michie, and former Hot Gossip dancer Carol Michie – have told The Sun newspaper they do not believe there was “any malice” involved in her time at the festival.
They said in a statement their “hearts are broken by the horrific tragedy” and Ms Michie “(appears) to have taken an illegal substance”.
A 28-year-old man, who was known to Ms Michie, was arrested on suspicion of murder and supply of a controlled Class A drug and has now been released under investigation.
Police would not confirm which Class A drug he was believed to have supplied.
Initial post-mortem results showed no clear signs of an assault, and further tests will now establish if there were any substances in her system or other suspicious circumstances.
Ms Michie, who was a dancer and model, had also taught yoga in Dalston, East London.
Mr Michie, 66, previously told The Sun the family had lost their “angel” and described the death as “a tragic mistake, a tragic accident”.
Describing his daughter as “positive”, “bright” and “full of energy”, he said “she touched so many lives”.
Mr Michie has two other children, Daisy, 27, a stylist, and Samuel, 26, a music video director.
Bestival organisers have said they are “devastated” by the death and are supporting police with the investigation.
With performers including Dizzee Rascal, Pet Shop Boys and Laura Mvula, this year was the first time the four-day festival was held in Dorset, having previously taken place on the Isle of Wight.