The father of an Australian woman found dead in Mozambique says his family has been let down after a coroner was unable to rule whether her death was a homicide.

Victoria’s state coroner Judge John Cain released his findings into Elly Warren’s death on Friday, more than seven years after the 20-year-old died in the African nation.

The Melbourne woman had spent a month volunteering but was due to return home on November 13, 2016, so she could start a marine biology course.

Instead, she was found dead outside a toilet block in the beach town of Tofo on November 9.

A Mozambique autopsy found homicide was her medico-legal cause of death, by suffocation on sand. The coroner found it was unlikely she was intoxicated and there was no evidence of drugs in her system.

But Cain could not rule whether the 20-year-old’s death was a homicide. He found the cause of death was aspiration of sand but he could not determine how the sand ended up in her lungs.

Cain could also not say whether Warren’s death happened outside the toilet block or if her body was moved there. He could not determine whether the 20-year-old had been sexually assaulted, although it was a possibility.

Cain said it was also possible that a person or multiple people caused or contributed to her death.

He pointed to the Mozambique authorities’ decision not to hand over the brief of evidence as the reason for his limited findings.

“It is possible that the Mozambique authorities do have information that is relevant to this investigation,” Cain said in his findings.

“But I do accept that release of any material held by the Mozambique authorities is a matter entirely in their discretion.”

Warren’s father Paul said he was disappointed Cain did not make a concrete ruling on her death.

“I think there is overwhelming evidence my daughter was murdered,” he said outside court.

“The Australian authorities have blatantly told us where they stand … and it’s back in the hands of Mozambique.

“I think Australia has let the family down.”

An instructing judge in Mozambique will need to determine whether investigators should continue to probe Warren’s death or if the case should be closed. Cain urged the judge to reach a conclusion as soon as possible for the benefit for Warren’s family.

When it came to the Australian Federal Police’s involvement in the case, Cain stopped short of any recommendations.

He found the AFP had made repeated attempts to provide assistance to Mozambique investigators but those requests had been largely ignored.

Cain was not critical of the police force but did urge them to develop better communication guidelines for supporting families like Warren’s.

Warren said the AFP had let down his family horribly. He said he would continue to fight for answers for his daughter.

“She was vibrant. She loved going overseas,” he said.

“She was a daughter that any father would be proud of.”

– AAP