A former Scotland Yard detective says he is hopeful a breakthrough can be made in the search for missing British child Madeleine McCann.
Portuguese police have been criticised for how they handled the disappearance of the 3-year old from a holiday apartment in Portugal six years ago.
A new television reconstruction will be aired next Monday on the BBC which is hoped it may trigger someone's memory or encourage those who may know something to come forward.
On Friday it emerged that Scotland Yard detectives investigating the disappearance of Madeleine McCann in 2007 are analysing the mobile phone details of everyone who was in the Portuguese holiday resort from where she disappeared.
There are around three dozen British police officers working on what has been designated Operation Grange, but the officers leading the investigation say there has been increasing cooperation with the authorities in Portugal.
Six Portuguese police officers based in Faro have been appointed to liaise with officers in London. The Metropolitan Police stress that they are "professional and committed" and were not involved in the original investigation, which remains closed.
Assistant Commissioners Mark Rowley and Detective Chief Inspector Andy Redwood are also sending formal International Letters Of Request to 30 other countries asking for assistance with their inquiry, reflecting the range of nationalities likely to have been in the town on May 3, 2007.
Detectives want to cross reference mobile phone data with other lines of inquiry, especially with individuals they have previously identified as "persons of interest".
The Portuguese authorities closed their investigation after initially investigating her parents Kate and Gerry as possible suspects. The UK Home Office agreed to order a review of the case by the Metropolitan Police and in July it became a full blown investigation.
Officers have been looking into the backgrounds of 41 individuals, 15 of whom are UK nationals.
Former Scotland Yard detective John O'Connor says a more focused investigation may uncover more information.
"I think she was taken by somebody who had planned it...it doesn't seem to me the way it was done that ti was that professional, it seemed to me they had every likelihood of being caught" he said.
"So this isn't some crime that's been carried out by some criminal mastermind - which is why I think that a determined investigation should, at the very least, unravel the mystery of what happened to her" he added.