Oxford teenager Martha Fernback post-mortem tests 'inconclusive'
More tests are to be carried out on the body of a teenage girl who suffered a cardiac arrest in an Oxford park after taking a drug thought to be ecstasy.
Martha Fernback, 15, from the Oxford area, had taken what she thought was MDMA (ecstasy) at Hinksey Park on Saturday, police said.
They said post-mortem tests proved inconclusive and toxicology test results would take at least six weeks.
A 17-year-old boy held in connection with her death has been bailed.
He was arrested on suspicion of possession with intent to supply a controlled drug and bailed until 5 September.
Det Insp John Turner said: "While our thoughts are with the family at this time, our focus is to establish the exact circumstances which led to Martha's death."
Her family described her as "effervescent" and "extraordinary".
In a statement they said: "We are all utterly devastated and have sought such comfort in the beautiful condolences we have received from everyone.
"All her family and friends felt so privileged to have known her."
Martha suffered a cardiac arrest at Hinksey Park near South Oxford Community Centre in Lake Street just after 13:00 BST.
Paramedics were called and she was taken to hospital by air ambulance where she later died.