The man accused of assassinating UnitedHealthcare’s CEO may have sparked even more violence through his alleged ideological motivations, federal prosecutors now contend.

Luigi Mangione -- the suspect in the December 2024 murder of insurance executive Brian Thompson -- has become the focus of a new legal claim by federal prosecutors who say his extremist writings may have influenced a deadly mass shooting at NFL headquarters in July 2025, as ABC News reports.

According to court documents filed by prosecutors, Mangione allegedly gunned down UnitedHealthcare CEO Brian Thompson on a Midtown Manhattan street using a 9 mm handgun outfitted with a silencer. After the fatal shooting, he evaded authorities during a five-day manhunt that ended with his capture in Altoona, Pennsylvania. Law enforcement arrested him without incident.

During an initial court appearance in New York on Feb. 21 of this year, prosecutors began laying the foundation for a case that portrays Mangione as more than just a lone killer. They allege that he operated with ideological intent and aimed to incite further violence.

Motive rooted in political ideology

Investigators say Mangione had a clear motive: targeting the health insurance industry. Found in his possession after arrest was a notebook in which he allegedly wrote, “The target is insurance” because “it checks every box.”

Authorities say this statement reflects a broader anti-establishment ideology. They allege Mangione believed violence was a viable means to achieve political or ideological objectives, a factor they are using to justify seeking the death penalty. Prosecutors believe the murder was intended to spark outrage or fear targeting the health sector. They claim Mangione hoped that dramatic violence would resonate with others and provoke wider unrest.

Bizarre bullet inscriptions raise alarm

Further troubling details emerged when investigators revealed that the bullets used in the December killing were reportedly marked with the words “deny,” “depose,” and “delay.” Prosecutors argue that these inscriptions reflect a deliberate and premeditated message aimed at furthering Mangione’s anti-corporate crusade. They emphasize that the use of such language on ammunition reflects intention beyond just killing Thompson. Instead, they say Mangione wanted to communicate a symbolic message tied to broader political discontent.

This chilling attention to symbolism and ideology, according to the prosecution, is now influencing others and leading to similar acts of violence by those who align themselves with Mangione’s beliefs.

July mass shooting puts Mangione's legacy into focus

On July 28, a second act of violence unfolded in Midtown Manhattan. Shane Tamura -- armed with an assault-style rifle -- opened fire inside the NFL’s headquarters on Park Avenue, killing four individuals before being subdued.

Following this second tragedy, Tamura was found to have left behind a letter accusing the NFL of exacerbating cases of chronic traumatic encephalopathy (CTE), a brain condition linked to repeated head injuries among athletes and military veterans. A former high school football player, Tamura never played at higher levels, but prosecutors now suggest his violent outburst was symbolically aligned with Mangione’s ideas -- targeting institutions that, in their view, exploit or harm people under the guise of corporate or entertainment interests.

Prosecutors cite “cult-like” following

In new filings, government attorneys allege that Mangione’s supporters are increasingly embracing violence as a tactic. They warn that his influence, even behind bars, continues to fuel instability. "The defendant hoped to normalize the use of violence," prosecutors stated, arguing that Mangione’s ideological impact poses a continued risk to public safety. They also cite his “own admission” that violence was intended to have ripple effects beyond one victim.

The prosecution is pursuing the death penalty against Mangione, citing both the brutality of the act and his broader attempts to inspire like-minded individuals to act violently.

Defense challenges prosecution efforts

Despite these alarming claims, Mangione has pleaded not guilty to the murder of Thompson. His defense attorneys have requested more evidence to challenge the death penalty justification. Prosecutors responded by stating that all evidence underlying the aggravating factors has already been shared. They insist there is "no risk of surprise" in their sentencing arguments.

While the defense prepares for trial, federal authorities continue to stress that Mangione’s influence goes beyond a single crime scene, pointing to what they view as an emerging extremist threat underpinned by his rhetoric.

Lessons to learn

1. Take emerging threats seriously, even if they don't seem immediate. Authorities say Mangione had a defined ideological motive before his crime. Awareness of extremist symbols, language, or behavior may help identify risks before they escalate.

2. Stay alert in public spaces, especially at facilities tied to politics, media, or corporate power. Both the Thompson assassination and the NFL shooting occurred in high-profile areas in the heart of Manhattan. While crime can happen anywhere, exercising healthy caution in these environments is advisable.

3. Understand that online and ideological influence can lead to real-world harm. Authorities allege Mangione developed a following that adheres to violent principles. While free speech is protected, signs of incitement to violence must not be ignored by communities or law enforcement.

Regardless of precautions, it's important to remember that crime can occur to anyone, anywhere. The responsibility for preventing violence rests primarily with the perpetrator, and we must avoid blaming victims for actions they could not foresee or control.

Why This Story Matters

This case sheds light on the growing risk of ideologically motivated violence and the role individuals can play in spreading dangerous messages. It reminds the public and officials alike that one act of violence can ripple into broader societal harm.

Moreover, the story emphasizes the importance of early intervention, awareness, and the need for comprehensive oversight when it comes to both legal and ideological threats. It serves as a wake-up call about the potential consequences of ignoring warning signs.