The U.S. government denied "eavesdropping" on UnitedHealthcare CEO murder suspect Luigi Mangione's recorded jailhouse calls in a Monday court filing after his defense attorneys claimed federal officials shared his calls with the Manhattan District Attorney's Office (DANY).

In the filing, prosecutors with the Southern District of New York initially said a paralegal with DANY's office "encountered" the call between Mangione and his New York-based defense attorney, Karen Friedman Agnifilo, on April 22, and "immediately stopped listening and reported the issue." In an amended Tuesday letter, however, prosecutors admitted that the paralegal listened to the whole call.

"The earlier letter stated that a DANY paralegal recognized the call as an attorney-client communication and immediately stopped listening. In fact, the paralegal listened to the entire call, then subsequently informed DANY prosecutors about the identities of the people with whom the defendant spoke," federal prosecutors wrote. "DANY thereafter handled the matter as described in our previous letter. Moreover, DANY notified defense counsel of these facts in an email, dated April 22, 2025, thus, counsel was aware of this information prior to arraignment."

The letters come after Friedman Agnifilo said during Mangione's Friday arraignment on April 26 that one of his jailhouse calls with her was recorded and "eavesdropped on" by a member of the DANY’s team, noting that the DANY office informed her that one person listened to the call. 

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Luigi Mangione appears in court

Luigi Mangione appears in Manhattan Criminal Court for a status hearing in New York City on Feb. 21, 2025. Magnione is accused of killing UnitedHealthcare CEO Brian Thompson. (Curtis Means/Pool)

"To be sure, no one at DANY or the Government ‘eavesdropped’ on the defendant on a live basis," federal prosecutors previously wrote in the Monday filing. "Rather, consistent with well-known practice in federal and state jails, many of the defendant’s calls are recorded, with notice of the recording provided to him and the person on the other side of any calls."

Prosecutors added that "a number of calls" between Mangione and Friedman Agnifilo "were provided by the Metropolitan Detention Center ('MDC') to the Government – and by the Government to DANY – because the defendant spoke to his counsel on a recorded and monitored jail line (not a line specially designated for attorney calls) and with counsel using a telephone number that was not identified as belonging to counsel (thus evading MDC’s process for filtering attorney calls before providing them to the Government)."

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Luigi Mangione appears in Manhattan Supreme Court in New York City

Luigi Mangione appears in Manhattan Supreme Court in New York City on Dec. 23, 2024. (Curtis Means for DailyMail/Pool)

"In any event, no member of the federal prosecution team has listened to any recording of any attorney call, and the Government has segregated all recordings of these attorney calls so that they cannot be accessed further," prosecutors wrote on Monday.

The government said it is "standard practice" for jail calls to be recorded through MDC's call system, Trufone network, which plays a recording whenever a defendant makes a call stating that the call is being recorded and is subject to monitoring. The government has so far received two sets of recordings in the Mangione case from MDC, which it then provided to DANY.

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Luigi Mangione is escorted by NYPD into a van after being extradited from Pennsylvania for the murder of United Healthcare CEO, Brian Thompson.

Luigi Mangioni is escorted from an NYPD helicopter in New York City, Dec. 19, 2024. (Rashid Umar Abbasi for Fox News Digital)

During Mangione's April 25 arraignment, during which he pleaded not guilty to federal charges in connection with Thompson's murder, Friedman-Angifolo said her office was "just informed by the state court prosecutors that they were eavesdropping on all of Mr. Mangione's calls."

"They were listening to his attorney calls and his other calls that are going on, and they said that it was inadvertent that they listened to a call between Mr. Mangione and me, who I am the lead counsel of record. And they know that, and obviously the United States knows that as well," she said. "And they said that these calls were given to them by the Southern District, and they're being recorded at MDC. … They took steps to minimize any encroachment into the attorney-client relationship and no one discussed with the one person who did listen, and that it was inadvertent."

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Brian Thompson in a blue button down shirt and blue zip-up smiles for the camera

UnitedHealthcare CEO Brian Thompson was killed on Dec. 4, 2024. (AP Photo/UnitedHealth Group)

She continued: "But we would just ask that the Southern District put something in place to ensure that no calls to his legal team and among the legal team are either recorded or listened to, certainly not provided to the Manhattan DA's Office or the U.S. Attorney's Office."

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ACCUSED CEO ASSASSIN LUIGI MANGIONE INDICTED ON FEDERAL CHARGES

Mangione was indicted in the Southern District of New York on charges of stalking and murdering Thompson on Dec. 4, 2024, as well as using electronic communications, interstate travel and a firearm when he allegedly killed the healthcare insurance CEO.

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Luigi Mangione departs the courtroom following his arraignment

Luigi Mangione departs the courtroom following his arraignment in New York City Criminal Court on Dec. 23, 2024. (Rashid Umar Abbasi for Fox News Digital)

The suspect allegedly shot Thompson outside the Manhattan hotel where UnitedHealthcare's annual shareholder conference was being held, in an act prosecutors believe was meant to send a message to the healthcare insurance industry based on a manifesto found on the suspect when he was arrested days after Thompson's murder.

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If the 26-year-old is convicted of murder through the use of a firearm, Mangione could face the death penalty, as federal prosecutors have indicated in court filings.

Fox News' Adam Sabes contributed to this report.