OLD BLACKSMITH BLOG

http://blacksmithbureau.blogspot.co.uk/2013/07/contamination.html
Intresting read i thought

Yes, in Kate's book they scolded the PJ for answering press questions about the crime scene contamination, the officer was "sheepish" because the press got him to answer about the contamination, and Kate reports with self satisfaction that the POLICE dogs had messed up the room, not they themselves.

however, the fact that they themselves touched and interfered with everything, their friends were all in and out etc shades and windows and cupboards all touched well before police were called makes it unfair to blame the cops for this! Had they not brought tracking dogs in McCanns would have screamed nothing was being done - do you really want all the DNA in the house processed before you get the dogs on the trail?

Agree with blacksmith they may not have done it on purpose but they surely did destroy any evidence on the one place they should not have touched at all, window/shutter.