The trial of a former narcotics detective for the New York Police Department who was accused of using false evidence to build criminal cases ended abruptly on Tuesday after a judge found that prosecutors had failed to turn over evidence to the detective’s lawyers.
The dismissal of the charges against the detective, Joseph Franco, a 20-year veteran who became a symbol of police misconduct, dealt a major blow to the Manhattan district attorney’s office. The agency immediately removed the prosecutor handling the case, Stephanie Minogue, from her position as the deputy chief of its Police Accountability Unit.
Mr. Franco had been charged in 2019 with 16 criminal counts, including perjury and official misconduct. Prosecutors said that he had lied about witnessing drug transactions that he could not have seen. In Manhattan, more than 100 convictions were vacated based on his involvement in the investigations, as were more than 130 in the Bronx and another 90 in Brooklyn.
The prosecution of Mr. Franco was cut short when Ms. Minogue’s team failed in three instances to hand over evidence to the former detective’s lawyer, a major ethical violation. The case was dismissed with prejudice: The office will not be able to prosecute Mr. Franco for the same crimes again.
A lawyer for Mr. Franco, Howard Tanner, said in a statement that his client was relieved at the outcome but asked, “How does he get his reputation back?”
“A decorated police officer who honorably served this city for 20 years, he never did anything wrong,” Mr. Tanner said. “This case was baseless and driven from the start by an anti-police agenda in the Manhattan D.A.’s office.”
He added that prosecutors had repeatedly withheld and destroyed evidence, and that they had misrepresented facts.
In a statement, a spokesman for the district attorney’s office, Doug Cohen, announced Ms. Minogue’s removal, saying, “New Yorkers must know that law enforcement, including prosecutors, are acting with the utmost integrity. We hold ourselves accountable to that standard.”
Mr. Cohen’s statement said that prosecutors had consented to a motion from Mr. Franco’s lawyer to dismiss the case, which was immediately sealed. He added that the office’s Post-Conviction Justice Unit, which reviews wrongful convictions, would continue to scrutinize cases in which Mr. Franco was involved.
The office said that it would analyze what had gone wrong in the case against Mr. Franco, though it did not immediately say whether that would involve a review of other cases in which Ms. Minogue was involved, such as the successful convictions in March of two officers who stole money during a periodic “integrity test” that the Police Department conducts. She remains employed by the office.
The trial’s abrupt ending was an embarrassment for the Manhattan district attorney, Alvin L. Bragg, who campaigned on improving police accountability. Mr. Franco’s trial, which began two weeks ago, was the most serious proceeding against a police officer that Mr. Bragg had overseen.