UnitedHealthcare CEO Brian Thompson was fatally shot Wednesday outside a Midtown Manhattan Hilton.Luigi Mangione was arrested and faces a murder charge in the killing.The killing of the 50-year-old father of two sparked a manhunt in New York City and beyond.Luigi Mangione, the suspect in the shooting death of UnitedHealthcare CEO Brian Thompson, is fighting his extradition to New York City, where he'll face a murder charge in the Midtown Manhattan killing.The 26-year-old Ivy League graduate appeared for a hearing on Tuesday at Pennsylvania's Blair County Courthouse where his lawyer told the judge that Mangione was contesting his extradition.Mangione, who was arrested on Monday on local charges and later arraigned, made a bail request, which the judge denied during the hearing.The suspect will remain at Pennsylvania's Huntingdon State Correctional Institution as the extradition proceedings play out.Thomas Dickey, Mangione's lawyer, told reporters later on Tuesday that Mangione will plead not guilty to all the charges in Pennsylvania.In New York, an arrest warrant obtained by Business Insider shows Mangione faces a second-degree murder charge in connection to the fatal December 4 shooting of Thompson, a 50-year-old father of two from Minnesota. That charge carries a maximum sentence of life in prison.(A charge of first-degree murder is reserved for those accused of killing a law enforcement official or witness of a crime, or for when a murder is committed during the commission of another high-level crime, including robbery, rape, or kidnapping.) Mangione also faces four other charges related to the killing of the insurance CEO: two counts of criminal possession of a weapon in the second-degree, one count of second-degree criminal possession of a forged instrument, and one count of criminal possession of a weapon in the third-degree.During Mangione's Monday arrest in Altoona, Pennsylvania, officers found a three-page handwritten document "that speaks to both his motivation and mindset," New York Police Department Commissioner Jessica Tisch said at a press conference later that day.An internal NYPD report obtained by The New York Times gave the clearest view of the potential motive yet. Based on the so-called manifesto that was discovered, Mangione "likely views himself as a hero of sorts who has finally decided to act upon such injustices," the NYPD report said, as reported by the Times.Mangione "appeared to view the targeted killing of the company's highest-ranking representative as a symbolic takedown and a direct challenge to its alleged corruption and 'power games,' asserting in his note he is the 'first to face it with such brutal honesty,'" according to the NYPD report by the department's Intelligence and Counterterrorism Bureau, the Times reported.In a statement to BI, representatives for Nino Mangione a Maryland state legislator and a cousin of Mangione's declined to comment on the news of Mangione's arrest."Unfortunately, we cannot comment on news reports regarding Luigi Mangione," the statement read. "We only know what we have read in the media. Our family is shocked and devastated by Luigi's arrest."Recognized at a McDonald'sMangione was eating in an Altoona McDonald's when an employee recognized him from the several surveillance images that authorities released in the aftermath of Thompson's killing and called the police, New York police said at the Monday press conference.Altoona police found Mangione in the McDonald's with multiple fake IDs and a US passport, as well as a firearm and a suppressor "both consistent with the weapon used" in the shooting of Thompson in the heart of Manhattan, Tisch, the NYPD commissioner, said.The gun appeared to be a "ghost gun" that may have been made on a 3-D printer with the capability of firing a 9-millimeter round, NYPD Chief of Detectives Joseph Kenny said at the press conference.A Pennsylvania criminal complaint filed against Mangione said officers found a black 3-D-printed pistol and 3-D-printed silencer inside the suspect's backpack.When Altoona officers questioned Mangione and asked him if he had been to New York recently, he "became quiet and started to shake," the criminal complaint said.Clothing, including a mask, was also recovered "consistent with those worn" by the suspect wanted for Thompson's killing, along with a fake New Jersey ID matching the ID that the murder suspect used to check into a Manhattan hostel before the attack, Tisch said.Based on the handwritten document that police found on Mangione, according to Kenny, "it does seem that he has some ill will toward corporate America."During an interview Tuesday morning on NBC's "Today" show, Tisch said the "manifesto" revealed "anti-corporatist sentiment" and "a lot of issues with the health care industry.""But as to like particular, specific motive that'll come out as this investigation continues to unfold over the next weeks and month," the NYPD commissioner said.NBC News and The New York Times, each citing an unnamed senior law enforcement official, reported that the handwritten document read in part: "These parasites had it coming.""I do apologize for any strife and trauma, but it had to be done," it added, according to the reports.Police believe that Mangione acted alone.NYPD investigators traveled to Altoona on Monday to interview Mangione after Altoona officers took him into custody.Blair County District Attorney Peter Weeks said at Mangione's Pennsylvania arraignment that Mangione was carrying $10,000 in cash, including foreign currency, according to the Associated Press.Mangione disputed the amount in court. NYPD released images of the person of interest in Brian Thompson's killing. DCPI/NYPD Mangione was active on social mediaOn the social media site X, Mangione posted and amplified posts about technological advances like artificial intelligence. He also posted about fitness and healthy living.He frequently retweeted posts by the writer Tim Urban and commentator Jonathan Haidt about the promise and perils of technology.He also appeared to be a fan of Michael Pollan, known for his writing about food and ethics, and lab-grown meat. At the top of his profile was a header image with three images: a photo of himself, smiling, shirtless on a mountain ridge, a Pokemon, and an x-ray with four pins or screws visible in the lower back.Mangione founded a company called AppRoar Studios in 2015 while still in high school. AppRoar released an iPhone game called Pivot Plane that is no longer available.The two other cofounders of AppRoar could not be reached for comment.Mangione's X account has been deactivated. A spokesperson for YouTube said his three accounts on the platform were also terminated, but that they had not been active for about seven months.A manhuntMangione's arrest follows a nearly week-long manhunt.According to police, Manigone was born and raised in Maryland, and has ties to San Francisco, California. His last known address was in Honolulu, Hawaii.The New York Post, citing law-enforcement sources, reported that Mangione's mother reported him missing in mid-November.Kenny, the NYPD's chief of detectives, said that Manigone has no prior arrest history in New York and no known arrests in the US.A Luigi Mangione with a matching birthday and address received a citation for simple trespass for entering a forbidden area of a state park in Hawaii in November 2023. He pleaded no contest and paid a $100 fine."For just over five days, our NYPD investigators combed through thousands of hours of video, followed up on hundreds of tips, and processed every bit of forensic evidence DNA, fingerprints, IP addresses and so much to tighten the net," Tisch said at Monday's press conference announcing the arrest of Manigone.Thompson was shot multiple times on a Midtown sidewalk as he was walking toward the Hilton hotel. He was steps away from a side entrance to the hotel where he was set to speak at UnitedHealth Group's investor conference when a hooded gunman opened fire on him from behind.The chief executive of the nation's largest health insurer was struck at least once in the back and at least once in the right calf, police said.Surveillance footage showed the gunman firing his weapon as Thompson, wearing a blue suit jacket, walked several feet in front of him.The gunman fled the scene, first on foot and then on an electric bike, which he rode into Central Park before ultimately escaping from New York City, police said.Shell casings and bullets found at the scene had the words "deny," "defend," and "depose" written on them, according to multiple reports citing unnamed sources. BI couldn't independently confirm these details.In the aftermath of the attack, the NYPD offered a $10,000 reward for tips leading to the gunman's arrest, with the FBI offering a reward of up to $50,000 for information leading to his arrest and conviction.A spokesperson for UnitedHealth Group, the parent company of UnitedHealthcare, reacted to news of Manigone's arrest in a statement to BI, saying: "Our hope is that today's apprehension brings some relief to Brian's family, friends, colleagues and the many others affected by this unspeakable tragedy. We thank law enforcement and will continue to work with them on this investigation. We ask that everyone respect the family's privacy as they mourn."This story is developing and will be updated.