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(NEW YORK) — As Luigi Mangione pleaded not guilty Monday to state murder and terrorism charges in the brazen killing of UnitedHealthcare CEO Brian Thompson, supporters of the suspect continued to donate tens of thousands of dollars for a defense fund established for him, leaving law enforcement officials worried Mangione is being turned into a martyr.

Several online defense funds have been created for Mangione by anonymous people, including one on the crowdfunding website GiveSendGo that as of Tuesday morning had raised over $200,000.

The GiveSendGo defense fund for the 26-year-old Mangione was established by an anonymous group calling itself “The December 4th Legal Committee,” apparently in reference to the day Mangione allegedly ambushed and gunned down Thompson in Midtown Manhattan as the executive walked to his company’s shareholders conference at the New York Hilton hotel.

“We are not here to celebrate violence, but we do believe in the constitutional right to fair legal representation,” the anonymous group said in a statement.

The crowdfunding campaign prompted donations from thousands of anonymous donors across the country, many of them leaving messages of support for Mangione, including one person who called themselves “A frustrated citizen” and thanked Mangione for “sparking the awareness and thought across this sleeping nation.”

In a statement to ABC News, a spokesperson for GiveSendGo said the company “operates with a principle of not preemptively determining guilt or innocence.”

“Our platform does not adjudicate legal matters or the validity of causes. Instead, we allow campaigns to remain live unless they violate the specific terms outlined in our Terms of Use. Importantly, we do allow campaigns for legal defense funds, as we believe everyone deserves the opportunity to access due process,” the GiveSendGo spokesperson said.

The spokesperson added, “We understand the concerns raised by such campaigns and take these matters seriously. When campaigns are reported, our team conducts a thorough review to ensure they comply with our policies. While other platforms may choose a different approach, GiveSendGo’s core value is to provide a space where all individuals, no matter their situation, can seek and receive support, with donors making their own informed decisions.”

Other crowdfunding sites such as GoFundMe have taken down campaigns soliciting donations for Mangione’s defense.

“GoFundMe’s Terms of Service prohibit fundraisers for the legal defense of violent crimes,” the crowdfunding website said in a statement. “The fundraisers have been removed from our platform and all donors have been refunded.”

Amazon and Etsy have removed from their websites merchandise featuring Mangione, including T-shirts and tote bags reading “Free Luigi” and the phrase “Deny, Defend, Depose,” words police said were etched in the shell casings discovered at the scene of Thompson’s homicide.

“Celebrating this conduct is abhorrent to me. It’s deeply disturbing,” Manhattan District Attorney Alvin Bragg told ABC News senior investigative reporter Aaron Katersky in an interview last week. “And what I would say to members of the public, people who, as you described, are celebrating this and maybe contemplating other action, that we will be vigilant and we will hold people accountable. We are at the ready.”

When Mangione appeared in court Monday for his arrangement, more than two dozen young women, who had waited in the frigid cold outside the courthouse, said they were there to support the defendant.

Most of the women wore face masks and a few appeared visibly emotional as Mangione entered the courtroom.

“This is a grave injustice, and that’s why people are here,” one of the women, who said she arrived at the courthouse at 5 a.m., told ABC News.

Other supporters outside the courthouse chanted, “Free, free Luigi” and “Eat the rich,” and held signs reading, “People over profits” and “Health over wealth.”

Manhattan grand jury indicted Mangione last week on 11 charges, including first-degree murder in furtherance of terrorism. Mangione is also facing federal charges that could get him the death penalty if convicted.

Mangione’s attorney, Karen Friedman Agnifilo, raised concerns in court Monday that her client is being used by police and New York City Mayor Eric Adams as “political fodder.”

Angifilo also slammed last week’s extradition of Mangione back to Manhattan to face charges, calling Adams’ presence amid the massive display of force used in the transfer “the biggest staged perp walk I have seen in my career.”

“What was the New York City mayor doing at this press conference — that is utterly political,” she said, before referencing the mayor’s own criminal case. “The New York City mayor should know more than anyone the presumption of innocence.”

Retired FBI special agent Richard Frankel said suspects have received unsolicited support in previous politically charged violent crimes.

“We saw it with the Unabomber,” said Frankel, an ABC News contributor, referring to Ted Kaczynski, the mathematician-turn-domestic terrorist who blamed technology for a decline of individual freedom and mailed handcrafted explosives to targeted individuals between 1978 and 1995.

Frankel said Eric Rudolph, who detonated a bomb in Atlanta’s Centennial Olympic Park during the 1996 Olympic Games and carried out three additional bombings as he eluded capture for five years, also attracted supporters.

“In my opinion, they’re supporting individuals who have committed potentially terrorist acts, but it’s a politically charged act,” Frankel said.

Referring to the Thompson killing, Frankel added, “You can be up in arms about the health care industry, but you can’t threaten or actually hurt members of the health care industry.”

Most recently, Marine veteran Daniel Penny was acquitted of criminally negligent homicide in the chokehold death of Jordan Neely, a homeless man who was acting erratically on a New York City subway, after supporters donated more than $3 million to his legal defense fund.

Law enforcement officials have expressed concern that Mangione is being turned into a martyr. Someone this week pasted “wanted posters” outside the New York Stock Exchange naming other executives.

A recent bulletin released by the Delaware Valley Intelligence Center, a multi-agency law enforcement intelligence-sharing network based in Philadelphia, included a photo of a banner hanging from an overpass reading, “Deny, Defend, Depose,” which are the same words etched on shell casings police said were recovered from the Thompson homicide scene.

“Many social media users have outright advocated for the continued killings of CEOs with some aiming to spread fear by posting ‘hit lists,'” the bulletin, obtained by ABC News, reads.

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