Half of all property crimes are localized in about 6.5 percent of the city. Spokane had the fourth-highest rate of auto theft in the U.S. in 2010 and 2011, according to the National Insurance Crime Bureau. Drive-by shootings and drug use, particularly crack cocaine use, became worse in the early 1990s, and four drive-by shootings were recorded in December 1993 alone. In the 1990s, the Spokane Police Department (SPD) established a special gang unit, with an officer "collecting intelligence on gang activity and disseminating it to street officers". The 1990s also saw Spokane's most prolific serial killer, Robert Lee Yates, who killed thirteen prostitutes in Spokane's East Sprague red light district and confessed to two others in Tacoma, Washington. The transition of the Spokane Police Department to a community-policing precinct model has helped curb crime rates since its introduction downtown, and has been expanded citywide. The crime woes are possibly due in part to an imbalance that Spokane County prisons receive of pre-release and work-release prisoners; An investigation by the "Tacoma News Tribune" found that while Spokane County accounts for 6.21 percent of the inmates in state prisons, it receives a disproportionate 16.73 percent of the inmate population to be released into the general population.