Seth Williams finds his ID as D.A.

Sitting in a cavernous, half-empty office, Seth Williams removed from his wallet a brand-new security badge - the unique, gold-bordered one that identifies him as the district attorney.

Not an assistant district attorney, which he was for 10 years, when he carried a red-bordered badge.

Not a candidate for district attorney, which he was in 2005 and again last year. And not the district attorney-elect, which he had been since November.

On his first full day on the job yesterday, Williams showed off his badge with a mixture of wonderment and pride, and talked about how he needs a little time to get used to the title and trappings.

"It was very different for me to have people come up to me and say, I'm the D.A.," he said.

Williams arrives in office with an ambitious agenda to change the way crime is prosecuted in Philadelphia, promising nothing short of making the city safer.

After a largely ceremonial inauguration day on Monday, he began those tasks in earnest yesterday, naming his leadership team, creating two divisions and outlining his priorities.

Monday "was a big day for me personally, after five years of trying to come back to the office I love," Williams said at a 10 a.m. news conference. "I recognize this job is much greater than the Seth Williams story. This job is about Philadelphia."

The sense of change was evident yesterday, down to the furnishings - or lack thereof - in Williams' office.

There were U.S. and Philadelphia flags flanking his desk, but nothing on the walls. Williams has a computer, but had yet to master the e-mail system.

His cherry desk with a mahogany stain was built by Philadelphia prison inmates in a job-training program.

His only decoration was a framed photo of the first contingent of African American Philadelphia police officers - a gift from one of his deputies, for the state's first African American district attorney.

"I love it," Williams said, smiling. "Spartan."

His inauguration party Monday was somewhat spartan as well. Instead of hosting a ball at a downtown hotel, Williams held a party at the Park Avenue Banquet Hall in Parkside that was open to the public for $25 at the door. The hall once hosted many of the parties Williams attended in high school, and is now owned by a friend.

His day began early yesterday, with an in-studio interview on the CW network, before holding the news conference at the District Attorney's Office.

Then came a succession of meetings, with his deputies and with the top brass from the Police Department, and another public appearance with the mayor and the police commissioner to discuss last year's crime statistics.

Williams faces some immediate challenges - such reviewing the case of an off-duty police officer who shot and killed an unarmed neighbor after a street brawl.

Somewhere along the line, the novelty of that coveted, gold-bordered badge should fade. But Williams is unlikely to forget the day he went to Police Headquarters to pick up his identification.

The technician producing the badges didn't recognize him and asked what job he was taking. Williams told him, "District attorney."

The technician pulled up the menu of positions, began scrolling through the list and asked again which was the correct title. Williams told him, again, "District attorney."

"He looks at me and he's, like, 'Oh my God, you're Seth Williams.' "