Ms Evans' lawyer, Carrie Goldberg, claimed that the prosecutors' decision not to oppose the dismissal of the charge had seen them "abandon" her client.
The letter also said prosecutors had recently obtained an email that Evans wrote in 2015 to the man she later married. "We are moving full steam ahead". Rather, "it only speaks volumes about the Manhattan D.A.'s office and its mishandling of my client's case".
US-based tabloid website TMZ reported last week that a casting director claimed Evans once told her she performed oral sex on Weinstein to gain an acting role. The detective is accused of hiding information about the witness and getting the witness to stay quiet about what she was allegedly told.
"Sexual assault is a serious crime", Brafman said outside the courthouse in Lower Manhattan Thursday, "but falsely accusing someone of sexual assault is also a serious crime".
Goldberg detailed how prosecutors used Evans for months and "put her through needless torture".
The 66-year-old father of five, out on a $1 million bail and forced to wear a Global Positioning System monitor, has long pleaded not guilty to six counts allegedly committed against three women in 2004, 2006 and 2013.
The witness reportedly told this to an NYPD detective past year.
Brafman, Weinstein's lawyer, told the judge he believes Evans lied both to the grand jury and to The New Yorker about her encounter with Weinstein.
Brafman asserted again that Weinstein has not committed any crime and said he planned to file an application with the New York Police Department asking the detective who interviewed Evans to be banned from the case.
Evans claims Weinstein forced himself on her, but the witness says otherwise.
"I think this grand jury is irreparably damaged".
Prosecutor confronted the detective, who admitted he'd failed to turn over the damning details, but denied discouraging the witness from cooperating. The union represented New York City police detectives also didn't immediately return a message.
The New York Post, never known for its restraint, blasted out a headline just before the judge dismissed the sexual assault count, wondering if the D.A.'s case is "in danger of falling apart".
More than 75 women have publicly accused Weinstein of wrongdoing.
Manhattan's district attorney dropped part of the criminal case against Weinstein on Thursday. "Nothing in this disclosure impacts the strength of the remaining case and the other five counts", she said, including the most serious count, for predatory sexual assault. 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.
"This is not about suggesting that a woman who comes forward should not be believed", Brafman said in a press conference. The former movie producer pleaded not guilty to all of them and was granted bail at $1 million.