Excellent article in the Mirror today.

http://www.mirror.co.uk/opinion/news-opinion/madeleine-mccann-disappearance-7-years-3490078

Peter Kirkham, a former Metropolitan Police detective has written exclusively for mirror.co.uk on the case

Today marks the seventh anniversary since Madeleine McCann went missing from an apartment in Portugal where she was sleeping while her parents ate at a restaurant with friends nearby.

Peter Kirkham, a former Metropolitan Police detective, has written exclusively for mirror.co.uk saying that he believes the disappearance is likely to be a mystery that will never be solved.

It’s now seven years since Madeleine McCann disappeared in Praia da Luz.

Tens, if not hundreds, of thousands of hours of investigation have been carried out by the Portuguese police, the private investigators employed by the McCann family and detectives from Scotland Yard.

But what has the investigation achieved?

Although recent developments have given the impression that significant progress is now being made, analysis shows that remarkably little is known with any certainty.

This case is, in the language of detectives, most definitely a “sticker”.

As in any investigation, the police need to establish what happened and prove who did it. In this case, unusually, they are unable to do either.

Pretty much all that has been established for sure is that Madeleine went missing during the night, whilst staying with her family in the Portuguese holiday resort.

Although there are numerous theories as to what may have happened to her, no evidence has been found which conclusively proves or disproves any of them.

All, therefore, remain possible hypotheses which the investigators must keep in mind.

The investigation – and the extensive worldwide publicity – has failed to find any direct witness to what happened on the night of May 3 2007.

The nearest the police have got is two witnesses reporting that they saw a man carrying young children nearby.

One of those sightings has eventually been eliminated.

The other has only led to a description and an artist’s impression of a possible suspect.

No-one has yet identified them.

It has been suggested that the crime scene was not initially secured as well as it could have been and some physical trace evidence could have been lost.

Whether or not that is the case, we know there is no fingerprint or DNA sample from the scene from which a suspect can be identified.

Scotland Yard detectives have recently identified two other lines of enquiry.

The first involves tracing a number of people who mobile telephone records place in the area at the time and who have not previously come forward.

The second relates to a linked series of sexual assaults on young children in tourist apartments around Praia da Luz at the time.

The first of these may lead to new information from a new witness, but I think it unlikely.

The second is more promising.

One of the hypotheses is that Madeleine was taken away by someone for a sexual motive.

If a suspect for the series of offences can be identified and traced there is a possibility (but nothing more) that they may be connected with the disappearance of Madeleine.

The longer cases like this go on, the more unlikely it is that they will be solved.

But the police will continue to follow-up all viable lines of enquiry and, sooner or later, if there is some breakthrough evidence there to be found it will come to light.

But I think there is a distinct possibility that this case will turn out to be one of those real, genuine mysteries which is never solved.

That said, as time goes on there is one thing which becomes more likely and that is a call from someone who knows what happened and who has been keeping it secret all this time.

It may be an offender or someone close to them.

But the passage of time, especially with such a high-profile case, makes it ever more difficult to keep the secret.

If there is someone out there with such information, that call could come at any time and when it does it will break the case wide open.