Madeleine McCann police have been given the go-ahead to quiz 10 key witnesses they have never spoken to before.
The breakthrough came after their fifth international letter of request was accepted by a new Portuguese prosecutor.
Ines Sequeira has paved the way for a new British police visit to the Algarve by approving a fifth international letter of request which had been gathering dust following her predecessor’s departure in the summer.
Officers in Faro are now scheduling the interviews, which will take place at the PJ police station in the town where four suspects were quizzed at the start of July.
It was thought three of the suspects would be given a new grilling when the Operation Grange team led by DCI Andy Redwood returned to Portugal.
Respected Portuguese daily Jornal de Noticias said Scotland Yard opted out of asking for permission to reinterview the suspects in their fifth letter of request, which state prosecutors received in August.
Around 10 witnesses are expected to be quizzed, including some who were questioned by Portuguese police after Madeleine vanished from her holiday apartment in Praia da Luz more than seven years ago. The unnamed witnesses are expected to receive police summons in the next few days.
As happened during the July round of interrogations, British police will sit in on the interviews but they will be led by Portuguese officers who will ask questions on their behalf.
The Operation Grange team last visited Portugal three weeks ago.
A small team of three officers including DCI Andy Redwood met Policia Judiciaria bosses in Faro for an update meeting before travelling to the university city of Coimbra a five hour drive north to visit a lab where many of the DNA samples collected after Madeleine’s disappearance are held.
They are yet to send a sixth international letter of request which mum-of-four Mrs Sequeira will have to authorise before Met Police forensics experts are allowed access to the lab or given permission to take samples to Britain to analyse them.
The forensic material includes hairs and pieces of the curtains that hung in apartment 5A at the Ocean Club holiday complex where Madeleine was sleeping with baby siblings Sean and Amelie, now nine, while her parents Kate and Gerry ate tapas nearby.
It emerged last week nearly 100 strands of hair tested during the original Madeleine McCann investigation were never DNA-matched.
Portuguese forensic experts analysed 444 hair strands they believed could hold the key to the youngster’s May 3 2007 disappearance.
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They found 432 were human and 12 non-human.
They were unable to DNA-match 98 of them and only obtained partial results from 19 of them, it was reported last week.
Institute president Francisco Brizida, said after the October 14 meeting: “I have the certainty they went away very happy.
“The tonic of the meeting was about the possibility of the tests on samples collected in 2007 being re-done. “The British police wanted clarification on the examinations the institute had carried out during the early stages of the inquiry in the areas of genetics and biology.
“We talked about non-identified material that was collected in Madeleine’s apartment.
“I can’t say for sure new DNA tests that didn’t yield a conclusive result in 2007 could now yield an objective result.
“But technology nowadays allows us to go further than years ago in areas like genetic markers.
“Several possibilities are open. One could be that British police do the tests in Britain with British technology and another that the institute does them.
“But that’s an area in which the institute does not have the last word. There’s a situation of judicial cooperation and a new international letter of request would be necessary.
|Operation Grange detectives in Portugal|
They dug up waste ground and inspected sewers in Praia da Luz in June in a grim search for her body. One of the suspects questioned in July was a former Ocean Club worker and another a 51-year-old schizophrenic drug addict.
They both denied any involvement in Madeleine’s disappearance. Portuguese police believe Madeleine was snatched by a foreigner no longer living in Portugal.
However they have not ruled out the involvement of junkie burglar Euclides Monteiro, whose widow they questioned last year.
Last month it emerged the cost of the British police search for Madeleine will soon top £10million - double the original amount estimated by the Home Office when the force was called in by David Cameron in 2011.
The Home Office has defending the rising cost of the probe, insisting: “The Government believes it is right that it does all it can to support the search for Madeleine McCann.”