The D.C. Public Defender Service's board of trustees, torn by conflict over the recent resignation of the service's director and the choice of a successor, selected former prosecutor Cheryl Long last night to head the office.

Long was one of two principal contenders for the job to direct the independent city agency of 61 lawyers, which annually represents more than 1,000 indigent defendants charged with serious crimes.

One faction of the 11-member board had backed the service's deputy director, Charles Ogletree, on the ground that he had the defense and supervisory experience needed for the job.

Board members, including Chairman Vincent H. Cohen, refused to comment on the selection. Long could not be reached for comment.

Long was a prosecutor in the U.S. attorney's office, then handled cases in its civil division before moving to the Justice Department, where she is enforcing federal environmental laws.

One official in the prosecutor's office described her as "very bright," but said he was "shocked" by the choice. "Ogletree was a very able advocate," the official said. "It's surprising to me that with someone with such credentials inside, they would go to somebody outside."

Francis D. Carter, who resigned as director last month, said he was concerned that "up until this point she has been a professional prosecutor," making it "extremely difficult for her to gain the confidence of both the legal community and the staff."

Royce C. Lamberth, chief of the U.S. attorney's office civil division, predicted, however, that Long "will win over the staff" with her abilities as an "able advocate" and a person who gets along well with people.

The job currently pays about $59,000 annually, but the board has the power to set a new salary level.