The ghost gun allegedly in Luigi Mangione’s possession when he was arrested in Pennsylvania has been matched to three shell casings found at the scene of Brian Thompson’s murder in New York City, NYPD Police Commissioner Jessica Tisch said Wednesday.
Fingerprints found from a water bottle and a Kind bar near the crime scene have also been matched to Mangione, she said.
Mangione, a 26-year-old Ivy League graduate, is accused of gunning down Thompson, the UnitedHealthcare CEO, outside a midtown Manhattan hotel on Dec. 4. Mangione was apprehended in Altoona, Pennsylvania, on Monday after nearly a week on the run.
Mangione allegedly had a spiral notebook with detailed plans on how to eventually kill the CEO, according to law enforcement officials.
One passage allegedly said: “What are you doing? You’re punching the CEO at the annual parasitic bean counter meeting,” the officials said.
The documents said using explosives in the attack could “endanger innocents,” according to the officials.
Detectives are still examining Mangione’s writings, but believe the contents of the notebook represent a confession, sources said.
Investigators have begun interviewing members of Mangione’s family, according to sources.
A Pennsylvania judge ordered Mangione held without bail on Tuesday. In Pennsylvania, he faces charges including allegedly possessing an untraceable ghost gun.
Mangione plans to challenge his extradition to New York, where he faces charges including second-degree murder.
“He has constitutional rights and that’s what he’s doing” to challenge the interstate transition, defense attorney Thomas Dickey told reporters Tuesday.
Mangione is “taking it as well as he can,” Dickey added.
The Manhattan District Attorney’s Office said it will seek a gubernatorial warrant to try to compel Mangione’s extradition. New York Gov. Kathy Hochul said in a statement that she will sign a request for the governor’s warrant “to ensure that this individual is brought to justice and held accountable.”
Mangione’s attorney told ABC News’ “Good Morning America” Wednesday that anyone speculating in the case should take the potential evidence “in its entirety,” and not take writings or other evidence “out of context.”
“People put out certain things, parts of different things,” he said. “I think any lawyer involved in this situation would want to see the whole thing.”
Mangione plans to plead not guilty to the charges in Pennsylvania, Dickey said. Dickey said he expects Mangione will also plead not guilty to the charge of second-degree murder in New York.
ABC News’ Sasha Pezenik, Mark Crudele, Luke Barr, Peter Charalambous and Josh Margolin contributed to this report.