Three months after authorizing Dominique Strauss-Kahn’s swift indictment after his arrest on sexual assault charges, the Manhattan district attorney, Cyrus R. Vance Jr., has decided to ask a judge to dismiss the case, a person briefed on the matter said on Sunday.

Mr. Vance’s decision will end one of the most closely watched prosecutions in New York in decades with no determination on whether the encounter between Mr. Strauss-Kahn, who was then the managing director of the International Monetary Fund, and a hotel housekeeper who went to clean his suite was criminal or consensual, several law enforcement officials have said.

While there has been widespread speculation that Mr. Vance would drop the case, it is nonetheless an extraordinary turn of events, for both Mr. Strauss-Kahn, 62, an enormously powerful international banker and a leading candidate for the French presidency before his arrest, and his accuser, Nafissatou Diallo, a 33-year-old immigrant from Guinea.

Her credibility as a witness began to crumble after prosecutors discovered what they characterized as a series of lies she had told, though none bore directly on her version of the encounter with Mr. Strauss-Kahn.

Mr. Strauss-Kahn, who was led out of a police building in handcuffs in May and held under house arrest until his bail conditions were relaxed last month, would be free to return to France after a judge, responding to a motion from the district attorney, formally dismissed the seven-count indictment.

The outcome would leave Ms. Diallo with no recourse to pursue criminal charges against the Frenchman. But she has filed a civil lawsuit seeking unspecified monetary damages from Mr. Strauss-Kahn for what the suit called a “violent and sadistic attack” that humiliated and degraded her.

Mr. Vance’s office has readied a motion known as a dismissal on recommendation, which one person briefed on the matter said would detail the reasons he and his aides believe that the case cannot be proved beyond a reasonable doubt.

Mr. Vance’s decision in the highly charged case, which ultimately became a credibility contest of sorts between Ms. Diallo and Mr. Strauss-Kahn, was said to have grown out of prosecutors’ assessment that her repeated lies, including multiple denials that she had given any consideration to Mr. Strauss-Kahn’s money, would open her to withering cross-examination. A day after the encounter, she and a friend who was in jail had a recorded telephone conversation about Mr. Strauss-Kahn’s wealth, a fact that the investigators would not learn until six weeks later, after Ms. Diallo had been asked repeatedly about the subject.

She is the only witness who could testify to the central allegation in the case: that Mr. Strauss-Kahn forced her to perform oral sex.

One law enforcement official involved in the investigation said no single problematic detail about Ms. Diallo’s background, or even all of them put together, had undermined the prosecution’s faith in its ability to present a viable case. Indeed, the official noted, it is common for witnesses and complainants who testify to be vulnerable to attacks on their credibility, either because their accounts have varied, or because they have self-interested motives for giving evidence, like avoiding jail or, occasionally, winning civil settlements.

In the Strauss-Kahn case, the official said, prosecutors came to believe that Ms. Diallo seemed unwilling to take responsibility for telling the truth.

“We deal with witnesses with these kinds of problems every day,” the official said. “With her, we had to drag the details of the lies out of her over weeks. It might have been different if she had let all the air out in a day or two. Every time she was confronted with her lies, she would blame someone else — someone told her to say this for asylum, someone else took advantage of her bank accounts, someone else did the taxes.”

Besides their legal and ethical responsibilities to disclose Ms. Diallo’s untruths, members of the prosecution team could have been called in a criminal trial to testify about her untrue statements to them — possibly transforming prosecutors into witnesses for the defense.

Asking a jury to believe Ms. Diallo beyond a reasonable doubt had become untenable, according to a senior official involved in the case.

“We couldn’t tell the jury that she kept lying to us but that they should believe her,” the senior official said.

Source: The New York Times