Susan Sward, Bill Wallace and Elizabeth Fernandez, with contributions from Lois Jermyn, of the San Francisco Chronicle used city police logs to create a database tracking the use of force by officers, finding that, for years, the San Francisco Police Department has failed to control officers who repeatedly resort to force, hitting, choking, clubbing and pepper-spraying citizens at rates far higher than fellow officers who patrol the same streets. A core group of fewer than 100 officers account for most of the incidents, but the SFPD has never done what the paper did in tallying the reports, which are kept on paper spread around stations throughout the city. "The department lags far behind many other major cities in developing an effective system for identifying problem officers. And it has failed, over and over, to take steps to get these officers off the streets." According to the investigation, officers with questionable records are promoted to supervisory positions or assigned to train rookies, putting them in position to carry forward a culture that tolerates or rewards the use of force. The series' main page includes more information on how the story was reported.