I am always taken back when I hear about such cases. Back here in Germany there are no rules against destroying evidence against you. We derive this from the fact that "you have the right to remain silent", meaning that no one can be forced to testify against himself. If law enforcement does not prevent the (alleged) destruction of evidence, that is bad luck for law enforcement.
On the other hand, search warrants are relatively easy to obtain and the fruit of the poisonous tree is legit in court for all but the most blatant cases, which have to be declared expressively by the judge.