British police have released pictures of the teenager who carried out one of the suicide bombings in London a week ago, appealing to the public for information about his final movements. The suspect, Hasib Hussain, was captured by security cameras at Luton station north of London at 7.20 last Thursday morning. He was carrying a rucksack. Peter Clarke, head of the Metropolitan Police’s anti-terrorism branch, said: “The question I’m asking the public is: did you see this man at King’s Cross? Was he alone or with others? Do you know the route he took from the station? Did you see him get onto a number 30 bus? And if you did, where and when was that?” A key puzzle is why the 18-year-old, unlike the three underground bombers, boarded a bus. An explosion ripped the bus apart nearly an hour after the three initial blasts, killing at least 13 people. On Thursday the overall number of known victims, excluding the suicide bombers, rose to 49, and police confirmed the fourth suspected bomber was Lindsey Germaine, a Jamaican-born Briton. Searches have continued in Aylesbury, where Germaine lived, and in Leeds, where the three other bombers came from. In the Beeston district, they carried out a controlled explosion after evacuating several streets. Meanwhile other suspects are being sought. One, suspected of masterminding the bombings, is described as a British-born al-Qaeda operative. He is believed to have left the country hours before the attacks. Another is an Egyptian chemistry student who disappeared from his Leeds home days before the blasts.