Seth Williams, 43, was sworn in at the downtown Kimmel Center for the Performing Arts as longtime incumbent Lynne Abraham looked on. A strong critic of Abraham, his former boss, Williams vowed to make changes to the office she had built up since 1991.
He lamented that Philadelphia has the lowest felony conviction rate among large urban areas in America and that it leads the nation in homicides by handguns. The DA's office, he said, needs to do just as much to prevent crime as it does to punish criminals.
"Crime prevention is just as important as crime prosecution," Williams said, vowing to make Philadelphia the safest big city in the country. "Four years from now, when I stand before you again, we will not have the lowest conviction rate in America."
Williams, a former city inspector general, plans to create a system in which prosecutors are assigned to neighborhoods in an effort to build trust.
He says the department needs to develop more partnerships with community groups, help to reduce truancy rates and make better use of technology in prosecuting crimes - including simple things such as text-messaging witnesses.
As he was sworn in, someone in the crowd shouted out, "You're making history!"
Mayor Michael Nutter noted that the city now had a black mayor, a black police commissioner and a black DA to deal with gun violence that is disproportionately affecting young black men.
"Three African-American men must come to grips with what I have referred to in the past as the black genocide," Nutter said, referring to himself, Police Commissioner Charles Ramsey and Williams.
In 2005, Williams narrowly lost to Abraham, the city's first female DA, when he challenged her in the Democratic primary. Last year, Abraham announced that she did not plan to run again.
In May, Williams defeated four other primary challengers and then easily beat little-known Republican Michael Untermeyer in the November general election. During the campaign, Williams had the backing of several key African-American groups, some of which have criticized Abraham for her aggressive pursuit of the death penalty.
Abraham earned the nickname "one tough cookie" from former Mayor Frank Rizzo and was once dubbed "America's deadliest DA."
She has not disclosed her plans. She said Monday that she planned to join a law firm soon and possibly announce another run for a different office in the near future.
"I leave the office in very good hands," she said. "Change is inevitable."
