Nobody has been arrested in connection with Monday's airport bombing, which left 35 people dead, and it is not clear whether the attack was carried out by one or two suicide bombers. Police are trying to identify the severed head of a male suicide bomber recovered from the scene and are trying to confirm whether he was accompanied by a female suicide bomber. Security sources said an apartment on the edge of Moscow thought to be a bomb-making factory was raided on 20 January but that it was empty. The Kremlin is under growing pressure to explain why its policy of pacifying the predominantly Muslim flank of southern Russia, which is used as a launch pad for such terror strikes, has failed. President Dmitry Medvedev fired Andrei Alexeyev, a senior transport policeman on Wednesday, pinning much of the blame on the police and the airport authorities. "Those who did not work properly must be punished," he said.