A new court filing details Luigi Mangione's diary entries in the months leading up to the killing of UnitedHealthcare CEO Brian Thompson, shedding light on how the murder suspect allegedly targeted the executive after initially planning a larger bombing attack.

The previously unreported entries were made public on June 4 in a filing by the Manhattan District Attorney's Office, which was submitted in response to a motion by Mangione's defense team seeking to stay or dismiss the New York state case against him.

"I finally feel confident about what I will do. The details are coming together. And I don't feel any doubt about whether it's right/justified," Mangione wrote in an entry dated Aug. 15, 2024, according to court records. "I'm glad-in a way-that I've procrastinated bc [sic] it allowed me to learn more about (UnitedHealthcare)," which he later describes as a company "that literally extracts human life force for money."

The writings go on to say that an attack Mangione initially planned would have been "an unjustified catastrophe," which would "do nothing to spread awareness/improve people's lives."

He added, "The target is insurance. It checks every box."

Mangione's attorneys did not immediately respond to a request for comment.

The writings come from a red notebook that was recovered when authorities took Mangione into custody at a McDonald's in Altoona, Pennsylvania, days after he allegedly shot and killed Thompson as he was heading to an investor conference in Manhattan on Dec. 4.

In April, Mangione was indicted by a federal grand jury on multiple charges including murder through the use of a firearm, which carries a possibility of the death penalty. Along with the federal charges and the New York case against him, he also faces several counts in Pennsylvania.

Mangione has pleaded not guilty to all the charges.

'Bomb the HQ? No.'

In October 2023, about six weeks before Thompson was killed, Mangione wrote that "the investor conference is a true windfall" because "It embodies everything wrong with our health system," court records say.

Mangione continued, describing his train of thought in targeting a CEO who was set to attend an annual conference for investors. "So say you want to rebel against the deadly, greed fueled health insurance cartel. Do you bomb the HQ? No. Bombs=terrorism."

He decided he should instead "wack [sic] the CEO" at the conference because it doesn't "risk innocents."

In the filing, prosecutors argue that the writings and Mangione's methodic planning of the attack justify the New York case and prosecutors' charge of first-degree murder in furtherance of terrorism.

"All of these writings convey one clear message: that the murder of Brian Thompson was intended to bring about revolutionary change to the healthcare industry. Defendant's targeting of UHC had nothing to do with anything that the company had done to him personally," wrote Joel Seidemann, assistant district attorney for the Manhattan District Attorney's Office.

"Brian Thompson and UHC were simply symbols of the healthcare industry and what defendant considered a deadly greed-fueled cartel."

Docs say Thompson passed Mangione on the street night before killing

In addition to the writings, the new docs shed light on Mangione's apparent stalking of Thompson before the executive was shot and killed on a Manhattan street.

Around 7:45 p.m. on Dec. 3, the evening before the shooting, Mangione could be seen walking on West 54th Street and Sixth Avenue, adjacent to the Hilton Hotel. Court records say he appeared to be talking on a cellphone.

As Mangione continued on the phone, Thompson walked past him in the opposite direction.

The next time Mangione would see Thompson was the following morning, when authorities say he waited for Thompson across the street from the hotel before walking up behind him and shooting him in the back.

At the scene, investigators found three cartridge shells with the words "deny," "delay," "depose," a likely reference to how insurance companies handle claims, court records say.

The shell casings at the scene matched the gun Mangione had in his possession when he was arrested in Pennsylvania. Additionally, Mangione's DNA was found on a cellphone, water bottle and several other items near the scene of Thompson's death.

Citing the evidence against, Mangione, Seidemann wrote, "If ever there were an open and shut case pointing to defendant's guilt, this case is that case. Simply put, one would be hard pressed to find a case with such overwhelming evidence of guilt as to the identity of the murderer and premeditated nature of the assassination."

This article originally appeared on USA TODAY: Luigi Mangione's diary entries unveiled in court documents

Reporting by Christopher Cann, USA TODAY / USA TODAY

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