During the stifling heat of summer, the al-Qubasi brothers liked to sleep on the flat roof of their Baghdad home. Twins Mustafa and Muhammed, at 12 years old the youngest in the family, were carrying their bedding on to the roof one evening in June this year. It was 10.30pm and bad timing, because the United States Army's 82nd Airborne Division was on night patrol. They shot Muhammed as Mustafa screamed for help. The army later said they mistook the bedding for an AK-47 assault rifle.