The national decline in both violent crime and property crime began in 1993, during the early months of Raymond Kelly's commissioner-ship under Dinkins. A firm believer in community policing, Kelly helped spur the decline in New York by instituting the Safe Streets, Safe City program, which put thousands more cops on the streets, where they would be visible to and able to get to know and interact with local communities. As the 37th Commissioner, he also pursued quality of life issues, such as the "squeegee men" that had become a sign of decay in the city. The murder rate in New York city had declined from its 1990 mid-Dinkins administration historic high of 2,254 to 1,927 when Kelly left in 1994, and continued to plummet even more steeply under Mayors Giuliani and Bloomberg. The decline continued when Kelly returned as commissioner under Mayor Bloomberg in 2002–2013.
The first World Trade Center terrorist attack occurred on February 26, 1993 while Kelly was police commissioner under Mayor Dinkins (1992 to 1994) and Kelly led his department through the investigation of the bombing.
In August 1993, Kelly introduced the 9mm semi-automatic pistol as an option for officers. The Glock 19, SIG Sauer P226, and Smith & Wesson 5946 pistols were approved for duty to replace the NYPD's Smith & Wesson Model 10 and Model 64 double-action only revolvers chambered in .38 Special. Himself a former street cop, Kelly was concerned about the semi-automatic pistols' propensity for sustaining firearm malfunctions. Indeed, at a media event introducing the new semi-automatic pistols in January 1993, one of the firearms malfunctioned just moments after a deputy inspector explained that malfunctions and failures were the semi-automatic pistol's major design drawback.
In November 1993, Rudolph Giuliani defeated Mayor Dinkins in his run for a second term as Mayor of New York City. Giuliani then replaced Kelly with Boston police commissioner William Bratton. Coincidentally, Giuliani and Kelly had known each other for a long time; they were two years apart at Manhattan College three decades previously.