SNIPPET: "Dinapoli said police already had a facial composite picture of the suspect they believe was behind the attack which killed 16-year-old Melissa Bassi." SNIPPET: "He said investigators had acquired "significant" video evidence that suggested one man had set off the device which exploded as pupils were getting off a bus for the start of lessons on Saturday morning. The footage showed a man of about 50-55 years of age activating a remote control to detonate a rudimentary bomb made of three gas canisters hidden in a container outside the school gates, he said."