There’s a new sign hanging over Interstate 83 in Baltimore.

“DENY DEFEND DEPOSE” read the handmade highway banner unfurled recently. “HEALTH CARE 4 ALL.”

The words were the message of a masked shooter who gunned down UnitedHealthcare CEO Brian Thompson on a Manhattan sidewalk on the morning of Dec. 4. Luigi Nicholas Mangione, the man from the Baltimore area charged with murder in Thompson’s killing, has emerged as a cause célèbre for anti-capitalists and those frustrated by the U.S. health care system, inspiring internet memes, a look-alike contest, even merchandise with the gunman’s credo.

The budding folk-hero mythology has alarmed law enforcement officials. At the White House Tuesday, press secretary Karine Jean-Pierre condemned the killing and addressed the speculation about the motive. “Violence to combat any sort of corporate greed is unacceptable.”

Still, the internet has been flooded with memes celebrating the 26-year-old Gilman School graduate from a prominent Italian-American family in the Baltimore area.

“And in this house, Luigi Mangione is a hero. End of story,” declared one viral post with an image of TV’s Tony Soprano in a bathrobe, pointing his finger.

According to an intelligence analysis report from the New York Police Department, Mangione “appeared to view the targeted killing of the company’s highest-ranking representative as a symbolic takedown,” The New York Times reported.

There was an element of theatre to Thompson’s killing, with messages on the bullets and an alleged escape by bike through Central Park, according to authorities. In what they say was the suspect’s handwritten manifesto, Mangione apologized for any “strife or traumas” but wrote, “These parasites simply had it coming,” according to The Associated Press.

“The fact that he’s white, the fact that he’s affluent, the fact that he’s handsome — it really creates a lot of drama that people lock on to and want to be part of,” said Joan Donovan, an assistant professor of journalism at Boston University, who recently published a book called “Meme Wars: The Untold Story of the Online Battles Upending Democracy in America.”

In many ways, the episode has taken on the contours of a television drama, Donovan said. A savvy vigilante pitted against a corporate giant — in this case, UnitedHealthcare. The public watched the story unfold in episodes: the suspect evading the police for five days, Monopoly money mysteriously left in backpacks, and photos of a smiling, handsome man captured by surveillance cameras circulating online. Then came the arrest — the grand reveal. On the internet, the fanfare was precipitous.

Donovan, who has spent years studying mass violence, said the elevation of alleged criminals to almost mythic status is nothing new. Usually, though, she said, such glorification happens in the darker corners of the internet, on far-right message boards steeped in bigotry and conspiracy theories. The idolization of Mangione, however, was different — fueled not by anonymity, but a relatively mainstream experience.

The flood of online support for Mangione reflects less about him as a person or the victim — Thompson, a married father of two — and more about a collective frustration with the health care system, Donovan said.

”What you’re seeing in people’s memes and discussions,” she said, “is how they rationalize this murder based on their own personal experiences of being denied care — usually when they needed it most.”

It is unclear if Mangione faced any such challenges after reportedly undergoing back surgery following a surfing injury.

Police arrested Mangione on Monday morning after receiving a tip that he had been recognized at a McDonald’s restaurant near Altoona, Pennsylvania. He was carrying a 3D-printed pistol, a black silencer and fake New Jersey driver’s license, Altoona Police wrote in charging documents. They recognized him from the “wanted” photos, they wrote.

When asked if he had been to New York recently, Mangione “became quiet and started to shake,” police wrote in charging documents.

Manhattan prosecutors filed murder and other charges against Mangione, according to an online court docket. He remained jailed in central Pennsylvania, where he was charged with possession of an unlicensed firearm, forgery and providing false identification to police.

Pennsylvania Gov. Josh Shapiro had sharp words for those who celebrate the suspect.

“In America, we do not kill people in cold blood to resolve policy differences or express a viewpoint. I understand people have real frustration with our health care system and I have worked to address that throughout my career. But I have no tolerance, nor should anyone, for one man, using an illegal ghost gun, to murder someone because he thinks his opinion matters most.

“In a civil society,” the governor added, “we are all less safe when ideologues engage in vigilante justice.”