DNA evidence from a New York hotel maid's clothes matches Dominique Strauss-Kahn, a source told The New York Times.
The source, speaking on the condition of anonymity, reported the police lab results to the newspaper.
The finding is in line with the woman's accusations of sexual assault against the former International Monetary Fund boss but also would be consistent with consensual sex, which his lawyers have floated as a defense.
DNA samples from a carpet also are being tested.
Strauss-Kahn, 62, is under house arrest in a Lower Manhattan apartment after being charged with forcibly assaulting the maid, a 32-year-old refugee from Guinea, at the Sofitel New York on May 14.
He denied all charges in a letter to the IMF staff, resigning his post.