DURHAM - Tracey Cline, an assistant district attorney who served under Mike Nifong during his misconduct in the Duke lacrosse case, announced on Tuesday her plans to run for district attorney.

Cline, a registered Democrat, has been a prosecutor in the Durham County District Attorney's Office for more than a decade, trying homicide, sexual assault and numerous other cases.

Now she wants to be the county's most powerful prosecutor, and she is campaigning on a platform of "justice for all people, all of the time."

Since Nifong's fall from power, questions have been raised about why prosecutors in his office did not expose his misconduct.

In a court hearing in mid-January, Judge Orlando Hudson, the county's chief resident Superior Court judge, said he and others in the courts should have picked up on problems sooner.

Cline said at her news conference in front of the Durham County courthouse Tuesday that while the lacrosse case was going through the system, she and other prosecutors were focusing on other cases.

Cline said it was "impossible," with cases being heard in four different courtrooms, for an assistant district attorney to go in and check behind the county's chief prosecutor.

Cline, now chief assistant district attorney, has come under fire by bloggers and other close followers of the lacrosse case for helping the investigators draw up an order for DNA testing of all but one member of the Duke lacrosse team.

But Tuesday, Cline was flanked by Butch Williams, a defense lawyer who represented a lacrosse team captain not charged.

Williams, a lawyer in Durham for 28 years who tried in the early weeks of the lacrosse case to quietly persuade Nifong to abandon his prosecution, described Cline as a Christian who has a compassion for the law and loves Durham County.

"That trio of qualities clearly is what I think sets Tracey clearly apart from all the other candidates," Williams said.

Freda Black, a former assistant district attorney who lost a bid to unseat Nifong in 2006, announced her candidacy nearly two weeks ago.

The Democratic primary is May 6, and a candidate must get a majority of the vote to proceed to the general election in November.

The filing period opened Monday.

Assistant District Attorney Mitchell Garrell, who worked as a prosecutor under Nifong, also has said he plans to seek the office.