DURHAM, N.C. — The accuser in the Duke lacrosse sexual assault case told prosecutors in December that one of the three players charged did not commit any sex act on her during the alleged attack, according to papers filed yesterday by the defense.

Reade Seligmann was repeatedly urged to take part in the alleged attack, the accuser told an investigator, but he said he could not because he was getting married, the papers said. Lawyers have said Mr. Seligmann, 20, has a girlfriend, but there has been no indication that he was engaged or married.

The description of Mr. Seligmann’s role in the alleged assault was one of several changes the accuser made in her account during a December 21 interview with an investigator from the district attorney’s office, the defense said.

In that same interview, the accuser also said she was no longer certain that she had been penetrated vaginally by a penis, a necessary element of rape charges in North Carolina. That led District Attorney Michael Nifong to dismiss rape charges against Mr. Seligmann and defendants Dave Evans and Collin Finnerty. The players remain charged with sexual offense and kidnapping.