A defense attorney for Luigi Mangione, the man charged with killing the CEO of UnitedHealthcare, insists a police search and arrest late last year were illegal.

A defense attorney for Luigi Mangione, charged with killing the CEO of UnitedHealthCare in New York City, says the police search and Mangione's arrest at a Pennsylvania McDonald's was illegal.

Accused United Healthcare CEO killer Luigi Mangione appeared in court on Friday, but no date was set for his trial.

Supporters of the accused UnitedHealthcare CEO killer gathered outside the Manhattan courthouse.

Alleged UnitedHealthcare CEO killer Luigi Mangione returned to a New York City courtroom on Friday for a brief appearance in his state murder case.

Luigi Mangione appeared in a New York City court today. He faces state and federal charges for allegedly shooting Brian Thompson, the CEO of United Health Care.

The afternoon appearance in Manhattan's State Supreme Court marks Mangione's first hearing since his arraignment on the state charges in late December 2024.

ABC News correspondent Trevor Ault shares the latest after Luigi Mangione is expected to appear in court as he faces charges for allegedly killing United Health Care CEO Brian Thompson.

The 26-year-old is expected to be in court for the first time since being charged with the murder of UnitedHealthcare CEO Brian Thompson outside a Manhattan hotel in December.

The accused killer of United Healthcare CEO Brian Thompson said he’s “overwhelmed by and grateful for” everyone who has expressed support for him.

Luigi Mangione, the accused killer of UnitedHealthCare CEO Brian Thompson, is speaking out from behind bars ahead of his next court appearance.

The accused killer has received more than $300,000 in donations as he fights murder charges in the shooting death of UnitedHealthcare CEO Brian Thompson.

Donations to Luigi Mangione’s legal defense fund have picked up after a news report that they had slowed down.

The firearm found on the suspect in the murder of the UnitedHealthcare CEO is believed to have been an untraceable ghost gun, according to police.

Luigi Mangione's defense team adds death penalty expert.

Supporters of Luigi Mangione are raising tens of thousands of dollars for his defense fund.

Luigi Mangione appeared in court on Monday in shackles and under heavy guard to plead not guilty in the murder of UnitedHealthcare CEO Brian Thompson.

Luigi Mangione appeared Monday morning before Judge Gregory Carro. The arraignment is in regard to 11 charges filed against him in the state of New York.

The alleged killer of UnitedHealthcare CEO Brian Thompson was extradited from Pennsylvania to New York City.

Protesters from all walks of life assembled outside the courthouse to show their support for Luigi Mangione

Mangione appeared on Monday in a Manhattan court for his arraignment on state murder and terror charges in the fatal shooting of UnitedHealthcare CEO Brian Thompson.

As investigators continue probing the United Healthcare CEO killing, there is concern among about the long-term impacts the public assassination could cause.

Luigi Mangione is due in a New York state court, where he will face charges in an 11-count indictment accusing him of murdering UnitedHealthcare CEO Brian Thompson “in furtherance of terrorism.”

ABC News’ Aaron Katersky and legal contributor Brian Buckmire discuss the court appearance for the suspect charged in the fatal shooting of UnitedHealthcare CEO Brian Thompson.

Luigi Mangione waived extradition on Thursday and was transported from Pennsylvania to New York.

Luigi Mangione is expected to face New York State murder and terrorism charges on Monday in a Manhattan court room.

Luigi Mangione, the man accused of gunning down UnitedHealthcare CEO Brian Thompson, is charged in a four-count federal criminal complaint.

The 26-year-old accused of shooting UnitedHealthcare CEO Brian Thompson arrived from Pennsylvania on Thursday. Mangione, who could now face the death penalty, has become an unlikely hero to some.

ABC News’ Linsey Davis speaks to criminal defense attorney Arthur Aidala on the criminal complaint filed today against Luigi Mangione and what happens next in the high-profile case.

Prosecutors laid out evidence against the 26-year-old accused in UnitedHealthcare CEO Brian Thompson's fatal shooting, after he arrived from Pennsylvania on Thursday. Mangione has not entered a plea.

Luigi Mangione faces four federal charges, including stalking, a firearms offense involving a silencer and murder through use of a firearm, a charge that makes him eligible for the death penalty.

Luigi Mangione, the man accused of gunning down UnitedHealthcare CEO Brian Thompson, waived extradition on Thursday morning.

ABC News’ Aaron Katersky and ABC News legal contributor Brian Buckmire discuss the federal charges against the suspect in the killing of UnitedHealthcare CEO Brian Thompson.

The suspect in the killing of UnitedHealthcare CEO Brian Thompson will “go forth with New York to await trial or prosecution for his homicide and related charges in New York.”

Mangione, the suspect in the killing of UnitedHealthcare CEO Brian Thompson, is set to return to court in Pennsylvania and is expected to waive extradition to New York, according to his attorney.

Luigi Mangione, the man accused of gunning down UnitedHealthcare CEO Brian Thompson, will waive extradition and could be returned to New York as soon as Thursday.

If his extradition paperwork goes through, the man accused of gunning down UnitedHealthcare CEO Brian Thompson will be cleared to travel from Pennsylvania to New York as early as Thursday.

Luigi Mangione, the man accused of gunning down UnitedHealthcare CEO Brian Thompson, will waive extradition to New York when he appears in court in Pennsylvania on Thursday.

Mangione was indicted in New York for the murder of UnitedHealthcare CEO Brian Thompson and the grand jury has upgraded charges to first-degree murder in furtherance of terrorism.

The man charged with murder for gunning down UnitedHealthcare CEO Brian Thompson was arrested and charged after the shooting outside a Hilton Hotel in Midtown Manhattan.

Luigi Mangione, the accused killer of UnitedHealthcare CEO Brian Thompson, is expected to waive extradition when he appears in court in Pennsylvania on Thursday.

Manhattan District Attorney Alvin Bragg said the Dec. 4 shooting of UnitedHealthcare CEO Brian Thompson was "intended to evoke terror." The 26-year-old remains in custody in Pennsylvania.

Luigi Mangione has been indicted in New York for the murder of Brian Thompson and the grand jury has upgraded charges to first-degree murder in furtherance of terrorism, prosecutors announced.

The accused killer of UnitedHealthcare CEO Brian Thompson is expected to waive extradition from Pennsylvania, where he was arrested a week ago, sources told ABC News.

Luigi Mangione was taken into custody in Pennsylvania on Monday following a dayslong manhunt for the suspect in the fatal shooting of UnitedHealthcare CEO Brian Thompson.

Sources tell ABC News the accused killer of UnitedHealthcare CEO Brian Thompson is almost certain to waive extradition from Pennsylvania, where he was arrested a week ago.

Luigi Mangione's mother filed a missing persons report about her son in San Francisco 16 days before he allegedly shot dead UnitedHealthcare CEO Brian Thompson.

Luigi Mangione, suspect in the murder of the UnitedHealthcare CEO, has hired high-profile defense attorney Karen Friedman Agnifilo, a former prosecutor with the Manhattan district attorney's office.

Mangione retained the services of Manhattan defense attorney Karen Friedman, a longtime veteran of the Manhattan District Attorney’s Office.

Luigi Mangione -- the alleged killer of UnitedHealthcare CEO Brian Thompson -- has been greeted by a surge of enthusiastic online support.