The UnitedHealthcare murder suspect's note contained the statement "these parasites had it coming," written by Luigi Mangione.

• In an Altoona, Pennsylvania, McDonald's, Luigi Mangione was detained by police and found with a handwritten note that read, "These parasites had it coming."
• Brian Thompson, the CEO of UnitedHealthcare, was murdered outside the Hilton Hotel in midtown Manhattan by Mangione, who was in possession of a gun and silencer at the time.
• An extradition hearing for Mangione will take place at the Blair County Courthouse in Hollidaysburg, Pennsylvania.

According to NBC News, Luigi Mangione was caught by Pennsylvania police and found with a handwritten note that read "These parasites had it coming" after being recognized as the suspect wanted for killing UnitedHealthcare's CEO.

Mangione, 26, claimed that he was not working with anyone when he allegedly fatally shot CEO Brian Thompson last Wednesday outside the Hilton Hotel in midtown Manhattan.

According to three law enforcement sources who spoke to NBC News, Mangione wrote in the note, "I do apologize for any strife or traumas, but it had to be done."

"Frankly, these parasites simply had it coming."

The broader U.S. health-care industry and corporations were criticized in a three-page note.

On Monday night, the Manhattan District Attorney's Office charged Mangione with murder and gun crimes in connection with Thompson's killing, following Pennsylvania authorities' earlier charges of firearms crimes and forgery against him.

Mangione will be in court at 1:30 p.m. ET on Tuesday in Hollidaysburg, Pennsylvania, for a hearing regarding his possible extradition to New York to deal with the murder case.

In the US, UnitedHealthcare, a subsidiary of, is the largest private health insurance benefits payer, generating over $280 billion in annual revenue.

The Hilton was the location of the UHG investor day meeting where Thompson, a 50-year-old father of two, was targeted and killed by Mangione, according to police beliefs.

In his note, Mangione stated that he would keep it brief for the Feds, as he respected their contributions to the country.

"I clarify that I acted independently and did not collaborate with anyone."

In Pennsylvania, Mangione, a wealthy Baltimore-area family member with chronic back pain, was charged with murder and gun crimes by the Manhattan District Attorney's Office hours after his arrest.

After being arrested in a McDonald's in Altoona earlier that day, he was denied bail Monday night and is currently being held in a state prison in Pennsylvania.

A man was reportedly acting suspiciously at a restaurant, prompting the Altoona Police to investigate.

Allegedly, Mangione provided officers with a fake New Jersey ID, which was later linked to his activities in New York prior to Thompson's murder. Eventually, he admitted to giving them his real name.

In his backpack, officers discovered a 3-D printed gun and silencer, along with ammunition, after taking him into custody. The weapon found is consistent with the one used to kill Thompson, according to New York police.

As of Tuesday morning, Mangione, a 2020 graduate from the University of Pennsylvania with both a bachelor's and a master's degree, had no attorney of record.

— NBC News' Tom Winter and WNBC's Jonathan Dienst contributed reporting