Ms Turner, 24, her mother Joan and her five-year-old daughter Shaunnah, were killed when Islamic gunmen opened fire on visitors to the ancient monuments near the Egyptian city last month.
A body flown back to Halifax, West Yorkshire, was originally believed to be that of the 24-year-old air hostess but dental records later proved it was not her.
The Halifax coroner Roger Whittaker said yesterday that Germany was now the most likely place for her body to be found.
This meant the body which had been returned to Halifax a few weeks ago could be that of a German which would mean Ms Turner had "more likely that not" been buried.
Mr Whittaker said that the German authorities had closed their files on all the bodies sent to them from Egypt and would only send dental records if requested to do so by police, but he added that Interpol had now been called in to retrieve the records from Bonn.
"I would have hoped they [the German authorities] would have co-operated without the need for a formal written request, and it is a great pity it has not materialised," he said.
Joan Turner's body was also missing at one point and had to be flown back from Switzerland to Halifax, near the family's home village of Ripponden. The Foreign Office said the mix-up began when a member of staff at the British Embassy wrongly identified a Swiss national as Mrs Turner before the body was flown to Britain. An unnamed family member also wrongly identified the body at Heathrow before a post-mortem was carried out.
Tragically for the family, of which there remains only one surviving member, Deborah, 30, the body of her sister is still missing.
An intensive search to find Ms Turner's body has covered Switzerland, Bulgaria, Japan, Colombia and South America after it was wrongly identified in Egypt.
The remains of the air hostess may also have been confused with those of one of the Egyptians killed in the massacre and remained in the country, although this is thought less likely.
It is feared the search could now involve exhuming bodies already buried. Some victims may have been cremated.
A Foreign Office spokesman said all that was possible was being done to swap dental records with other countries whose citizens were killed.
A funeral for all three generations of the family, which was originally scheduled for 27 November, has been delayed until Ms Turner's body is found.Reuse content