Well, although the Subject of this thread is a bit alarming, the following is (I believe) a rare case of police corruption, but it's something foreigners should be aware of and be ready to deal with, should it happen again:
Today's edition of El País, in Madrid pages brings the news of three policemen who have been convicted of the crime of stealing 4.900 euros to a group of 5 chinese travellers in Gran Via of Madrid in 2002.
After identifying them, they took their money and fled. They were in an undercover car and thought the travellers wouldn't take the car plates number, but they did.
When the chinese tourists went to the Precinct to report the theft, they faced those policemen, and there was a stir.