New York, United States — A 26-year-old man was arrested Monday after the targeted killing of a top health insurance executive on the streets of New York, police said, crediting a McDonald's employee in Pennsylvania who spotted a suspicious-looking customer.

Investigators were interrogating the man, Luigi Mangione, in connection with last week's killing of a senior figure at UnitedHealthcare, New York Police Commissioner Jessica Tisch said.

He is being held by officers in Altoona, Pennsylvania, after being found with a weapon that New York Chief of Detectives Joseph Kenny described as a "ghost gun" capable of firing 9MM rounds and equipped with a suppressor.

The man was spotted in a McDonald's in the town some 300 miles (500 kilometers) west of New York, by someone who tipped off the authorities, Tisch added.

He also had fake IDs similar to those used by the killer ahead of the slaying as well as a handwritten manifesto about the ills of the insurance industry, The New York Times said, citing a law enforcement source.

New York detectives were headed to Altoona, Tisch said, while Chief of Detectives Kenny said that Mangione possessed material that suggested he had "ill-will towards corporate America."

Police had been looking into the possibility that the shooter used a long-barrel veterinary gun — normally used to euthanize animals — to commit the murder.

The gunman walked up behind Brian Thompson, the senior executive at UnitedHealthcare -- one of the country's largest medical insurers -- and shot him dead last Wednesday in front of bystanders, in an attack captured by a surveillance camera and since seen by millions.

Thompson was attending an investor conference in the Midtown business district.

Ample video footage

Detectives said the suspect fled the crime scene on foot, before riding a bike to Central Park, and later boarding a bus from a terminal in the north of the city connecting New York to surrounding states and beyond.

Police would not confirm media reports that the words "delay" and "deny" — language often used by insurance companies to reject claims — were written on shell casings found at the scene.

Video footage shows Thompson on the sidewalk outside the New York Hilton Midtown when a man in a hooded top, his lower face covered, approaches from behind, then fires several shots at his 50-year-old victim, who crumples to the ground.

An image released of the smiling suspect was obtained from a youth hostel where the gunman apparently stayed before the hit, with media reporting he had lowered his mask to flirt with a receptionist.

Authorities subsequently located a gray backpack in Central Park thought to belong to the killer containing a jacket and Monopoly money, US media reported.

(Source: Gregory WALTON, AFP)