Police in the US say they may never know how Chandra Levy died.
Officers have confirmed that the Washington intern was murdered but investigators say they may never know how she was killed.
The city's chief medical examiner, Dr Jonathan L Arden, said there is no evidence to ascertain exactly what caused the 24-year-old's death. He concluded she was murdered because of the circumstances in which her body was found hidden in a secluded spot at a park in Washington DC.
Dr Arden said: "It's possible we may never know the specific injury that caused her death."
Dr Arden said that no DNA tests have been carried out on her body and no further tests are planned. He would not reveal when her remains will be released for burial.
The new developments were announced almost a week after Ms Levy was found dead and just hours before a memorial service was due to be held in her home town of Modesto, California.
Following the service, Ms Levy's parents Dr Robert and Susan Levy are expected to make their first public comments since she was found dead.
Ms Levy went missing just over a year ago and her body was found by a man walking his dog last week.
What initially seemed a routine, if baffling, missing persons' case hit the headlines in America because of Ms Levy's romantic links with Democratic congressman Gary Condit.
Police have named no one as a suspect in the death of Ms Levy although investigators are exploring whether the case can be linked to two assaults on women in the park last summer.