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On a Sunday afternoon, Douglas Zerby, 35, left a Long Beach bar feeling too drunk to drive home, walked to a nearby house, and sat on the stoop. While waiting for his friend to come home, he played with the nozzle from a nearby garden hose. A neighbor, mistaking it for a gun, called police. The officers who arrived on the scene did not announce their presence, identify themselves, or tell the seated man to drop what they believed to be a gun. They did shoot and kill him, later claiming that he pointed the hose nozzle at them. The Long Beach Police Department says they acted reasonably. The district attorney cleared them of criminal wrongdoing. And on Thursday, a federal jury awarded the dead man's family $6.5 million in a civil suit, concluding after brief deliberations that the officers acted negligently and violated Zerby's civil rights.

Would you want those officers patrolling your neighborhood? I wouldn't. I presume their mistake was an honest one. But making the right call in difficult, stressful situations is a crucial part of the job. And there's no mistake more serious than needlessly shooting and killing an innocent. I can't tell you exactly how often it happens -- or even how often police officers kill in general. "The nation's leading law enforcement agency collects vast amounts of information on crime nationwide, but missing from this clearinghouse are statistics on where, how often, and under what circumstances police use deadly force," Alan Maimon reports. "In fact, no one anywhere comprehensively tracks the most significant act police can do in the line of duty: take a life."