WASHINGTON – The special prosecutor who has spent nearly two years investigating the alleged involvement of White House officials in the leak of the identity of an undercover CIA employee is planning to make a public announcement on Friday, just as the grand jury reaches a deadline to return indictments in the case.

A spokesman for the prosecutor, Patrick Fitzgerald, declined to get into details last night about what will be announced, but confirmed that a statement is forthcoming on Friday.

The announcement should bring an end to a week of feverish anticipation and as politicians, pundits, and reporters in the capital waited to see whether top White House officials will be indicted in the probe. Lawyers for witnesses entangled in the inquiry continue to believe that at least one indictment is likely. Vice President Cheney’s chief of staff, I.Lewis Libby, is believed to be in the most serious legal jeopardy.Associates of President Bush’s top political adviser, Karl Rove, are also concerned that he could faces charges, though one person close to the case said last night that prosecutors have not warned Mr. Rove of an imminent indictment.

The case revolves around efforts to discredit a Bush administration critic, Joseph Wilson IV, whose wife, Valerie Plame, works for the CIA. Ms. Plame’s name, and her tie to the agency, appeared in the press in July 2003, soon after Mr. Wilson wrote an op-ed piece questioning the veracity of President Bush’s statements about alleged Iraqi efforts to gather nuclear materials.

The prosecutor is investigating whether the disclosure of Ms. Wilson’s identity broke the law, and whether there was an effort to obstruct his inquiry into the matter.Mr.Fitzgerald has said virtually nothing in public about what his investigation has revealed. However, at a court hearing in June, he said,”This case is about potential retaliation against a whistleblower.” Mr. Fitzgerald has also repeatedly cited a court opinion describing the conduct under investigation as “a serious breach of public trust.”