Mangione appeared in court in Pennsylvania on Monday, shortly after his arrest at a McDonald's restaurant in Altoona, Pennsylvania, following a five-day manhunt across multiple states. Mangione told a judge he was in touch with his family "until recently."
Law enforcement sources told ABC News that Mangione's mother spoke with a task force of FBI agents and New York Police Department detectives one day before her son's arrest on Dec. 9.
That conversation followed a tip the FBI received from the police in San Francisco, where Mangione's mother filed the missing persons report.
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The tip from SFPD was based on physical appearance and Mangione's mother, in her conversation with the Joint Violent Crimes Task Force last Sunday, indicated the person in the surveillance photos circulated by the NYPD could be her son, the sources said.
The task force was still working on the information the mother and San Francisco Police Department provided when Mangione, 26, was arrested in Altoona.
The Mangione family released a statement saying they were "shocked and devastated by Luigi's arrest" and offered "our prayers to the family of Brian Thompson and we ask people to pray for all involved."
Mangione is currently in custody at a Pennsylvania state prison after a judge denied bail on Tuesday. Mangione faces charges in Pennsylvania including allegedly possessing an untraceable ghost gun. In New York, he faces charges including second-degree murder.
Mangione's new attorney
Mangione has now hired veteran former New York City prosecutor Karen Friedman Agnifilo to defend him, according to a statement from her law firm Agnifilo Intrater LLP.
Friedman Agnifilo served as the second-in-command in the Manhattan District Attorney's Office from 2014 to 2021 under former District Attorney Cyrus Vance. A biography on her law firm website says she played a lead role in prosecuting "high-profile violent crime cases," including those involving mental health and cold case homicides.
"Karen Friedman Agnifilo has a three-decade background in criminal justice, litigation and trials. Her practice focuses on criminal defense in state and federal courts, leveraging her extensive experience prosecuting serious violent crimes, including complex homicide cases, from accusation to investigation to arrest and trial," the biography said.
"While serving in the Manhattan DA's office, Ms. Friedman Agnifilo was also integral to creating the office's Human Trafficking Unit, Hate Crimes Unit, Antiquities Trafficking Unit, Terrorism Unit, its Cybercrimes and Identity Theft Bureau, as well as working on the creation of Manhattan's first Mental Health Court," the biography continued.
Friedman Agnifilo is also a frequent television news guest and commentator and is a former legal analyst for CNN.
She is the co-host of a weekly podcast on the Meidas Touch Network where she discusses emerging legal issues and litigation strategy, and serves as a legal adviser for the television show "Law and Order."
Writings analyzed
Law enforcement sources told ABC News that writings seized from the suspect indicate he developed a fixation and increasing malice toward UnitedHealthcare and allegedly talked about harming its leader for months.
Some entries in the notebook seized from Mangione upon his arrest were dated as far back as mid-2024, the sources said.
That fixation eventually evolved into the alleged plan to shoot executive Thompson, the sources said.
Some of the writings were diary-style, documenting how he felt and what he did that day. They also documented a desire to focus on his health and find his purpose, the sources said.
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But as time went on -- and as Mangione allegedly fell out of contact with friends and family and grew increasingly isolated -- some writings indicated a deterioration in his state of mind, illustrating a gradual build towards the alleged plan to kill Thompson at what the writings described as UnitedHealthcare's "annual parasitic bean-counter convention," sources said.
Mangione's writings, obtained by ABC News, claimed that the U.S. has the most expensive health care system in the world but ranks around 42nd in life expectancy.
He said UnitedHealthcare "has grown and grown, but as our life expectancy? No the reality is, these [indecipherable] have simply gotten too powerful, and they continue to abuse our country for immense profit."
"I do apologize for any strife of traumas but it had to be done," he allegedly wrote. "Frankly, these parasites simply had it coming."
Neither Mangione nor his parents received insurance through UnitedHealthcare, according to UnitedHealth Group.