Police told one of Harvey Weinstein's accusers to remove any files from his phone that she wanted to keep private, prosecutors have admitted.
Assistant District Attorney Joan Illuzzi-Orbon said a detective told the author to "eliminate everything he did not want anyone to see."
Weinstein's lawyer said the development "undermines" the case.
The Hollywood producer faces charges related to alleged sexual assaults on two women. Mr. Weinstein denies the charges.
"My office asked plaintiff 2 to produce each and every cell phone she could have used during the time she interacted with the defendant," Ms. Illuzzi-Orbon wrote in a letter to Weinstein's lawyer, Ben Brafman.
However, he adds that the woman said that she was then recommended to delete the files "before providing the phones to our office."
Despite this advice, the woman still provided the telephones used to communicate with Mr. Weinstein "without any deletion," said Ms. Illuzzi-Orbon.
Mr. Brafman then issued a statement in response to the letter, saying that the news "further undermines the integrity of an already deeply flawed allegation of Mr. Weinstein."
Previously requested that the entire case be dismissed.
Earlier this month, a judge in New York rejected the charges against Mr. Weinstein by actress Lucia Evans, after it was said that he had given a different explanation of the facts.
Mr. Weinstein has been accused of sexual misconduct by more than 70 women.
The accusations against him helped to awaken the #MeToo movement, which has seen hundreds of women accusing high profile men in business, government and entertainment for sexual abuse and harassment.
Mr. Weinstein agreed to take a GPS tracker and deliver his passport.
He also faces additional investigations in Los Angeles and London, and by the federal government of the United States.
The 66-year-old lawyer, who has been on bail for 1 million dollars (£ 750,000) since his arrest in May, denies having sex without consent, his lawyers said earlier.