Shell casings found at the scene of the brazen murder of a US insurance executive match the gun found on the man charged with the crime, the New York police commissioner said Wednesday according to US media.
Suspect Luigi Mangione's fingerprints also matched those found near the crime scene, NYPD Commissioner Jessica Tisch added, quoted by ABC, confirming for the first time direct links between the suspect and the killing unearthed by detectives.
Mangione, 26, was arrested Monday when he was recognized at a McDonald's in Altoona, Pennsylvania following a tip from staff, with police finding a gun, fake IDs and documents discussing the crime and possible motives.
He remains in Pennsylvania as he fights efforts to extradite him to New York to face justice over the alleged targeted killing of UnitedHealthcare chief executive Brian Thompson last week.
He is accused of murdering Thompson on a Manhattan street outside a busy hotel hosting an investor gathering, triggering a nationwide manhunt and sending shock waves through corporate America.
The suspect's lawyer Thomas Dickey did not respond to an AFP request for comment, but previously told local media he had not "seen any evidence yet" implicating his client. He said Mangione denies the charges.
A week after the crime, detectives are focusing on what may have motivated the engineer, a University of Pennsylvania graduate from a wealthy Baltimore family, to allegedly shoot Thompson in cold blood.
Police have said that when he was arrested, Mangione had a three-page handwritten text criticizing the US health care system, which is often maligned for putting profits ahead of people.
He also had a notebook with him containing planning notes for the murder, The New York Times reported citing law enforcement sources.
"What do you do? You wack the CEO at the annual parasitic bean-counter convention. It's targeted, precise, and doesn't risk innocents," said one entry according to The Times.