A Detective Was Accused of Lying. Now 90 Convictions May Be Erased.

The Brooklyn district attorney will move to dismiss old convictions in which a former narcotics detective, accused of perjury in Manhattan, played a key role.

Over nearly two decades as a police officer and narcotics detective, Joseph E. Franco made thousands of arrests, many for the possession and sale of drugs. Mr. Franco often worked undercover, and his testimony secured convictions for prosecutors around the city. But officials who once relied on Mr. Franco are questioning his accounts. After he was accused of lying about drug sales that videos showed never happened, Mr. Franco was charged with perjury in Manhattan in 2019. Now, the fallout over Mr. Franco’s police work is spreading: As many as 90 convictions that he helped secure in Brooklyn will be thrown out, prosecutors plan to announce Wednesday. Many more cases in other boroughs could follow — a reckoning that lawyers said appears larger than any in the city’s legal system in recent history.