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The head of the Manhattan District Attorney Cy Vance Jr.’s vaunted Construction Fraud Task Force left her post this week after allegations surfaced that she withheld damaging evidence about a key cooperating witness in seven major bribery cases, THE CITY has learned.
Assistant District Attorney Diana Florence had prosecuted most of the high-profile cases involving construction wage theft, bribery and worker deaths brought by Vance in the last few years.
He appointed her “attorney-in-charge” of the task force when he formed it in August 2015 to crack down on wrongdoing in the industry.
Florence stepped down Tuesday shortly after allegations emerged in court papers that she kept secret a 38-minute audiotape in which the key informant in a series of construction bribery cases denied under oath to city investigators that he’d accepted any bribes.
Ifeanyi “Manny” Madu, a former city Department of Environmental Protection manager who was involved in picking vendors, was Florence’s star witness in cases she prosecuted against several contractors who’d received millions of dollars in city work.
Madu cooperated with the DA and claimed that in exchange for steering work to favored vendors, he received bribes of hotel stays, Broadway show tickets, gifts, extravagant meals and work for a subcontractor he secretly controlled.
He was the sole cooperating witness in seven criminal cases that were announced at an April 2018 news conference in which Florence stood next to Vance.
Unknown to the defendants, on Feb. 13, 2015, Madu made an audiotaped statement to city Department of Investigation agents involved in the bribery case, during which he was placed under oath.
According to court papers reviewed by THE CITY, Madu told DOI “among other things that he broke no laws, and that he did not take gifts, things of value or bribes from contractors.”
’Wishing Diana Well’
In court papers, Florence denied deliberately withholding evidence in the bribery cases, but did not address the allegation regarding the Madu DOI tape. She did not immediately return a phone message from THE CITY.
The allegations threatened to unleash a stampede to throw out cases and convictions involving Madu and Florence.
The accusations also marked the latest strife for Vance, who faces calls for his resignation over his handling of some high-profile cases involving the likes of Harvey Weinstein, Jeffrey Epstein and family members of President Donald Trump.
Vance, who hasn’t decided whether he’ll run for a fourth term, served on a task force that recommended in 2017 making judges order prosecutors to disclose evidence favorable to defendants at least 30 days before trial.

Manhattan District Attorney Cyrus Vance Jr. told staffer Thursday that another prosecutor was taking over Florence’s post.
Ben Fractenberg/THE CITY
On Thursday, Emily Tuttle, a spokesperson for Vance, declined to discuss Florence’s employment. But she did say that a new prosecutor, Assistant DA Rachana Pathak, was the new head of the construction fraud panel.
Vance released a brief statement about the reassignment Thursday, in which he asked that his employees join him in congratulating Pathak on her new job “and wishing Diana well.”
Vance’s spokesperson declined to comment on whether the DA’s office would be reviewing cases handled by Florence.
Last-Minute Evidence
By law, prosecutors are obligated to turn over all evidence that they gather when they bring a criminal case, including anything that could possibly exonerate a defendant. The DA’s office did not turn the Madu DOI tape over to defense attorneys in several cases in which he was the only cooperating witness, according to court papers.
Since the indictments, several of the defendants implicated by Madu — including the CEO and CFO of a major city contractor, HAKS Engineers — have pleaded guilty to various charges, including bribery and filing false documents.
Last month, one defendant, Henry Chlupsa, former president of D&B Engineers & Architects, began a non-jury trial prosecuted by Florence before Manhattan Supreme Court Justice Thomas Farber.
During the trial, Madu testified that he’d accepted bribes from Chlupsa, who has repeatedly denied the charges. Farber found Chlupsa guilty of second-degree bribery. Neither the judge nor Chlupsa’s attorney had been given the Madu DOI tape, court papers indicate.
The existence of that tape was disclosed last week in a court filing by Marc Agnifilo, an attorney for Kyriacos Pierides, a former associate vice president of the Kansas City-based engineering firm, Black & Veatch, who was also charged with bribing the prosecution’s star witness.
Pierides has denied bribing Madu. Since the 2018 indictment, Agnifilo has repeatedly demanded that the DA’s office — and Florence in particular — hand over all the evidence gathered in bringing bribery charges against his client. The trial was set to start Jan. 6.
On the eve of trial, Agnifilo said in court papers that the DA suddenly turned over nearly 15,000 pages of documents and other evidence — including the Madu DOI tape. Vance’s office also announced that a new assistant DA would be handling the case.
A week later, 135,900 emails suddenly turned up that Agnifilo says should have been given to him long ago.
Sea-Change Reforms
Prosecutors withholding evidence from defense lawyers until the last minute was a key concern addressed by criminal justice reforms that passed in Albany last year and kicked in on Jan. 1.
Under the changes to the process of pretrial discovery, prosecutors are required to turn over all evidence in most cases within 15 days of indictment and no later than 45 days, a marked change from the past.
Last week, Agnifilo filed court papers asking a judge to dismiss the charges against his client, noting the Madu tape that had been withheld from Chlupsa who found guilty with evidence “prosecutors have had since Feb. 13, 2015, five years ago.”
He called this “an error of constitutional dimension,” and declared: “The discovery violations appear to be intentional.”
In court papers she filed in response, Florence insisted most of the newly released evidence related to the broad investigation and was not specific to Pierides’ case.
She added that some of the material “comes from devices we inadvertently failed to analyze earlier.” She did not address the Madu DOI tape.
Florence previously handled several high-profile cases, including the June 2016 manslaughter conviction of a general contractor, Harco Construction LLC, in the death of laborer Carlos Moncayo.
The firm was charged with failing to address unsafe conditions at a Meatpacking District job site before Moncayo was buried alive when a trench he was working in collapsed.
She later testified about the case before the City Council during a hearing on the problem of contractors cheating workers on wages. Her testimony came two days before Vance announced the Madu-related indictments.
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