A judge agreed on Thursday to dismiss allegations by Lucia Evans, one of three accusers in the case.
Weinstein still faces a mandatory minimum of 10 years behind bars if convicted of predatory sexual assault.
In a statement released to CBS New York, the New York Police Department said it is "fully confident in the overall case it had pursued against Mr. Weinstein".
Harvey Weinstein (C) arrives at Manhattan Criminal Court for a hearing on October 11, 2018 in New York City.
The Sept. 12 letter from Assistant District Attorney Joan Illuzzi-Orbon to defense lawyer Ben Brafman was filed under a protective order, which Justice James Burke lifted Thursday.
There are still five criminal charges against the embattled producer involving two other women.
Weinstein's legal team argued in court papers that prosecutors hadn't properly identified the day on which Evans alleged she had been assaulted.
A year ago, Ms Evans told The New Yorker that Weinstein forced her to perform oral sex during a meeting at his office in 2004.
"When you do your homework after the arrest bad things happen", Brafman said. Nicholas DiGaudio interviewed a friend of Evans by telephone but told prosecutors she didn't want to cooperate, according to the filing.
Scottish couple named as Majorca flood victims
The deputy mayor of the town, Antonia Bauza, confirmed to Cadena SER radio that two others killed in the area were locals. Angela Alfaro had to spend the night in a shelter because a road section leading to Sant Llorenc had collapsed.
Weinstein appeared in Manhattan Criminal Court on Thursday morning as Judge James Burke chose to dismiss count six of the eight-count indictment against the 66-year-old film producer.
Brafman said that inconsistencies in Evans' account were initially discovered by a fact checker at The New Yorker.
In a statement, a lawyer for Evans said she was disappointed by the DA's decision to "abandon" her.
"Let me be clear: the decision to throw away my client's sexual assault charges says nothing about Weinstein's guilt or innocence". Later that evening, as they walked home, Evans allegedly told the witness that she had shown her breasts to Weinstein. Rather, "it only speaks volumes about the Manhattan D.A.'s office and its mishandling of my client's case".
A source familiar with the investigation told CNN at the time that the criminal sex act charge was from a case involving aspiring actress Lucia Evans, who alleged Weinstein forced her to perform oral sex on him in his Tribeca office in 2004.
Weinstein has pleaded not guilty and is free on $1 million bail.
Weinstein has been accused of misconduct by dozens of women, allegations that torpedoed his career and helped launch the #MeToo movement.
The collapse of part of the case against him could mean trouble for the prosecutor. At the time, Vance cited a lack of supporting evidence, despite the existence of a clandestinely made recording of Weinstein discussing the episode with the woman. Days later, The New Yorker published the first in a series of articles in which women brought forth allegations of rape, sexual assault, and sexual harassment against the film executive.
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