There must have been a swag of information coming into the McCann's investigation site.
There must have been ... indeed Scotland Yard managed to work that one out some time ago. So I think you can rest easy that Scotland Yard have covered all the obvious bases.
**Snip
The Home Office requested a review of the case in May 2011. Operation Grange, which has been supporting the Portuguese police's investigation, became a full investigation in July 2012.
The Met said in October that officers had finished bringing together and investigating the information held by Portuguese police, the UK investigation and
private investigators working on behalf of the McCann family.
The inquiry took 1,338 statements and collected 1,027 exhibits but has not yet reached a conclusion.
Officers investigated more than 60 persons of interest. A total of 650 sex offenders were considered as well as reports of 8,685 potential sightings of Madeleine around the world.
Having reviewed all of the documents, "7,154 actions were raised and 560 lines of inquiry identified", the Met said.
More than 30 requests were made to "countries across the world asking for work to be undertaken on behalf of the Met".
http://www.bbc.co.uk/news/uk-36138504