Backpacker Britt Lapthorne's body was immersed in water from the time she went missing in Croatia and her body was weighed down, a Victorian autopsy has found.

While the results of the autopsy have not been officially released, Ms Lapthorne's parents have revealed details to News Ltd.

Died in Dubrovnik ... Britt Lapthorne.

Ms Lapthorne, 21, of Melbourne, went missing from a nightclub in the Croatian city of Dubrovnik on September 18 last year. Her badly decomposed body was found in a nearby bay on October 6.

A report completed by the Victorian coroner late last year found Ms Lapthorne had been in the sea for the entire time she was missing and that there were marks on her remains from contact with marine life that dwell on the sea floor, News Ltd said.