Investigation: The Internal Security Agency provided the police investigators with relevant information very quickly after the attack; as the investigation continued this unusual level cooperation was maintained. The Agency's annual reports had routinely been flagging up right wing extremist groups as a danger to national security, which explained its long-term close interest in them. (a) April 30, 2009 The Czech Police Chief stated his firm belief that the perpetrators would be identified within a month. He also announced that for the police it was a matter of honour to find the perpetrators. (b) May 13, 2009 The police stated they were optimistic about finding the perpetrators of the attack. They were looking for a dark coloured car which had been seen at the scene of the attack. Meanwhile, it was now made public that the attack had involved the throwing of three Molotov cocktails. (c) May 27, 2009 As many as 500 people had by now been questioned about the arson attack. The police found the dark coloured car, but they reported that this had been a blind lead. Meanwhile the police let it be known that they were examining the theory that the attack had been an act of revenge, after an incident two months before the attack in which a car had hit a pedestrian in front of the house. The pedestrian had died. However, this later turned out to be an unrelated incident. While interviewing one of the suspects (without revealing any exceptional interest in him), police installed a tapping device in his car. Later, as the evident lack of police progress caused the suspects to relax, the tapping of this car would prove vital in solving the case