“Open and Shut”: The State’s Case Against Mangione, Part I

Breaking down the State of New York's 82-page response to the Defense's Omnibus Motion

Jun 09, 2025

I described Karen Friedman Agnifilo’s April 30th omnibus motion as the opening gambit of a high-stakes chess match. The motion to dismiss struck me like a pawn offering. Bold and tactical. Last week’s 82-page response from state prosecutors could be seen as the state accepting the defense’s gambit, thereby entering the complex legal game the defense has initiated.

That’s probably overstating it a bit, but after reading 82 pages of legal jargon, you might strain for a metaphor, too.

In this post, I’m just going to summarize Joel Seidemann’s affirmation in response to the defense’s omnibus motion (which can be found in its entirety here), because that’s how I roll when I’m trying to understand things. Summary first, analysis or speculation later.

What I will say is that the state’s response to the defense motion lays out a case with what appears to be substantial forensic evidence, extensive surveillance footage, and LM’s own writings, all pointing toward premeditation and “ideological” intent. Their argument for classifying the act as terrorism is weaker, in my opinion as a non-lawyer. I mean, arguing that wealthy investors are terror victims feels like a punch line, not a serious statement. Yet that is exactly what Seidemann does here.

And the case is, in his words, “open and shut.”

Just a shout-out to Joel Seidemann for his Regina George impression.

There’s always been a divide among those interested in the Mangione case between people who believe he is likely the suspect who murdered Brian Thompson and those who don’t think (or don’t want to believe) that he is. I’m not going to get into that here, and the statements of facts below should not be seen as an endorsement of Mangione’s guilt or innocence.

All I want to to in this particular post is lay out for you, and for me, a coherent summary of Seidemann’s 82-page motion responding to KFA’s April omnibus motion to dismiss terrorism charges. In my next post I will be taking a closer look at a few elements in the motion, but for now, here are the basics.

The What

Mangione is charged with first and second degree murder; murder as an act of terrorism; multiple weapons charges; and possession of a forged instrument (ghost gun). The state of New York argues that the murder of Brian Thompson was ideologically motivated and therefore constitutes domestic terrorism.

In this motion, the State contends the following:

LM used a 3D-printed ghost gun with a homemade silencer.

Surveillance cameras captured LM’s movements before and after the crime

The items found (backpack, water bottle, phone, gum) were linked to him via DNA and fingerprints.

Among his possessions when he was arrested in Altoona were the weapon used to kill Brian Thompson, a fake ID, cash, and a notebook.

“Manifesto” and Motive

The State contends (and shares some pages from the notebook to support their contention—more on that in a later post) that Mangione wrote at length about targeting Unitedhealthcare executives to protest the U.S. healthcare system, which he allegedly described as a “greed-fueled cartel.”

The State contends Mangione deliberately chose the UHC investor conference as a symbolic target to maximize impact and media attention.

And that he explicitly rejected random violence or bombings because he stated he wanted this act to be seen as precise, justified, and ideologically clear.

Statements to Law Enforcement

Getting into the legal arguments put forth in this motion, we can start with Mangione’ statements to law enforcement. As we know the defense seeks to suppress many of these. Seidemann doesn’t make an argument in these pages but agrees to a Huntley hearing to determine admissibility.

Suppression of Physical Evidence

In response to the defense’s argument that the search of Mangione’s backpack was unconstitutional, the State denies any rights violations, but consents to a Mapp hearing.

Non-Eyewitness Identification

Again, as we know, the defense has moved to keep lay witnesses familiar with Luigi Mangione off the stand (in other words, keep them from claiming to identify him in surveillance images or video). Here, the State is arguing that admissibility must be decided at trial based on any change in LM’s appearance, citing a 2024 case People v. Mosley, which allowed this kind of testimony depending on whether the defendant’s appearance had changed since the time of the crime. (I think we can all agree Mangione’s appearance hasn’t really changed since December 4th, 2024.)

Terrorism Charges

This is particularly interesting. The prosecution tries here to justify charging Mangione under New York’s terrorism laws by laying out several elements, including his alleged motive, the population targeted, and evidence they say proves this was an act of terrorism.

I’ll get into this in a different post, but overall, the prosecution is arguing three things. One, because the motive was not personal but ideological, it was intended to intimidate health insurance employees, influence policy, and even disrupt financial markets.

Two, that the terrorized population was civilian and included hundreds of thousands of UHC and health insurance workers. Though I’m trying to be as objective as possible, I have to admit to a chuckle that may or may not have turned into a guffaw when I read that Seidemann was referring to “investors and analysts” as terror victims.1

The idea that wealthy traders mildly impacted by a “disruption” to stock prices can be included in a statutory group termed “terror victims” is patently absurd and I feel that in casting the net that wide, Seidemann has made a major misstep. Anyway, for these reasons the State feels all this taken together satisfies the statutory definition of terrorism.

The fourteen victims of the New Orleans terrorist attack on New Year’s Day 2025.

Five of the “tens of thousands” of victims of Luigi Mangione’s “terrorism”

Three, that Mangione authored a manifesto speaking to his desire to make a statement through this act of violence, that he carved the words deny, depose, and delay on ballistics, and that the ensuing threats against UHC staff following the murder demonstrate intent.

The Agnifilos argued in their motion that there has to be multiple victims for a crime to be qualified as an act of terrorism, but here the State cites single-victim cases that had been prosecuted as acts of terrorism (1994 Brooklyn Bridge and 1997 Empire State Building shootings). I haven’t had time to look these cases up so I can’t speak to the strength of this particular legal argument.

Double Jeopardy Issues/Trial Delay

The Defense has argued that the state trial should come after the federal case. Seidemann argues that the state’s case is in a more advanced state of readiness than the federal case (not surprising, given the upheaval in the Southern District and the fact they filed their indictment four months after the state of New York). They also state that dual prosecutions by state and feds don’t violate the double jeopardy clause.

Overall, the State argues here that the evidence of Mangione’s guilt is overwhelming. That his actions were calculated, ideological, and aimed at influencing public policy, which, collectively, qualifies them as acts of terrorism under New York law. And that the court should deny the defense’s motion to dismiss terrorism charges and proceed with the suppression hearings.

Finally, because there’s been so much speculation about it over the last six months, here’s a summary of the DNA evidence the State claims it has that links Mangione to the crime.

Shell casings recovered from the scene were fired from the gun found on LM at the Altoona McDonalds, based on microscopic ballistics analysis.

DNA analysis matched Mangione’s DNA to the cellphone dropped near the scene of the murder; an Ethos water bottle he was allegedly seen drinking from in surveillance footage before the shooting; the backpack recovered from Central Park; a piece of chewed gum found in the same backpack (weird); and a Kind bar wrapper found in a trashcan near the Ziegfield Theater.

So, is this really an “open and shut” case, as Seidemann claims? That depends on which part of the filing you’re looking at, and how hard you squint. The forensic and surveillance evidence appear robust, and the notebook excerpts, at least as quoted, suggest intent (even if the style seems to have deviated from Mangione’s usual writing style, as seen in online postings, which is a conversation for another post).

But the terrorism charge is another story. When a legal argument hinges on whether market analysts can be considered terror victims, we’re in strange territory.

For now, though, we’re just walking through the state’s side of the board. In my next post, I’ll take a closer look at some of the more questionable arguments, look more closely at the so-called manifesto, and try to figure out whether this gambit, accepted or not, has actually gained either side an advantage.

As always, as ever, please note that I am not a lawyer though I wish I were. Would love to hear your thoughts on the State’s response to the defense’s omnibus motion.