The daughter of Holby City actor John Michie apparently took an "illegal substance" before her death at Bestival, her family has said.
Louella Eve Fletcher-Michie, 25, was found dead in a wooded area on the edge of the festival site at Lulworth Castle, Dorset, on Monday.
Dorset Police arrested musician Ceon Broughton, 28, who was known to Ms Michie, on suspicion of her murder and supplying a class A drug.
Mr Broughton, from London, was released under investigation on Tuesday after a post-mortem examination showed no clear signs of assault.
In a statement released through Mr Michie's agent, the family said: "Our hearts are broken by this horrific tragedy.
"We do not believe there to have been any malice intended in Louella and Ceon's weekend at Bestival.
"They appear to have taken an illegal substance but we would appreciate cautious and sensitive reporting until the facts are known.
"Louella inspired all who knew her with her joy of life. The family would like to thank everyone for their heartfelt tributes and messages."
Police said further tests, including a toxicology report, will take place over coming weeks to establish if there were any substances in Ms Michie's system or other suspicious circumstances.