The tool was first built for casinos to track big winners who have been banned but try to return to gamble under a different name, according to Onalfo. Running the software through the arrest and arraignment databases helped the NYPD create a clean database of 2 million unique criminal records -- eliminating 7 million duplicates. Onalfo also hopes to apply digital voice recognition to recorded emergency 911 calls in order to more easily search and store them, and his dream project is equipping NYPD's beat police with handheld devices.

There are, not surprisingly, similarities between Onalfo's NYPD job and his old private-sector posts. He leverages the NYPD "brand" to negotiate vendor deals. And he insists that all projects be broken down into manageable phases to lower the risk of failure.

But there are differences, too. A lot of decisions, even to promote employees, are out of his hands. And "at my first meeting, everybody was wearing their guns," Onalfo said. "I asked them to put their safeties on because I didn't want someone to pull out their weapon and say they disagreed with me."