The murder by a white police officer of an unarmed 19-year-old black man was the spark which ignited the accumulated tinder of racism and poverty in Cincinnati last week. In the biggest "race riots" since the Rodney King trial in Los Angeles in 1992, hundreds took to the streets to protest police brutality and the pent-up frustrations of decades of marginalization and poverty. Timothy Thomas was the 15th black male killed by the Cincinnati police since 1995, and the fourth since November. During the same period of time, no whites were killed by police. Officer Stephen Roach shot him as he evaded arrest for outstanding warrants - mostly traffic violations. Roach claims he feared for his life because he saw Thomas reach for a weapon during their encounter in a dark alley - but no gun was recovered at the scene. Like the Amadou Diallo case where the West African immigrant was shot 19 times just for reaching for his wallet, the case of Timothy Thomas highlights the fact that relations between one of the most oppressed segments of society and the police are balanced on a knife's edge, ready to explode at any moment.