There is no indication the man charged with killing the UnitedHealthcare CEO, Brian Thompson, was ever a client of the medical insurer and may have targeted it because of its size and influence, a senior police official said on Thursday.

Joseph Kenny, chief of detectives for the New York police department, told NBC New York in an interview on Thursday that investigators had uncovered evidence that Luigi Mangione had prior knowledge UnitedHealthcare was holding its annual investor conference in New York City.

Mangione also mentioned the company in a note found in his possession when he was detained by police in Pennsylvania.

“We have no indication that he was ever a client of UnitedHealthcare, but he does make mention that it is the fifth-largest corporation in America, which would make it the largest healthcare organization in America. So that’s possibly why he targeted that that company,” said Kenny.

Mangione remains jailed without bail in Pennsylvania, where he was arrested on Monday after being spotted at a McDonald’s in the city of Altoona, about 230 miles (about 370km) west of New York City. His lawyer said he had not seen any evidence yet linking his client to the crime.

Mangione’s arrest came five days after the killing of Thompson outside a Manhattan hotel was caught on camera.

Police say the shooter waited outside the hotel, where United Healthcare was holding its investor conference, early on the morning of 4 December. He approached Thompson from behind and shot him before fleeing on a bicycle through Central Park, then heading to a bus depot.

Mangione is fighting attempts to extradite him back to New York so that he can face a murder charge in Thompson’s killing. A hearing has been scheduled for 30 December.

The 26-year-old, whom police say was found with a “ghost gun” matching shell casings found at the site of the shooting, has been charged in Pennsylvania with possession of an unlicensed firearm, forgery and providing false identification to police. His lawyer, Thomas Dickey, said his client is not guilty.

Mangione is an Ivy League graduate from a prominent Maryland real estate family. On Wednesday, police said investigators are looking into an accident that injured Mangione’s back and sent him to an emergency room in July 2023. They are also looking at his writings about the injury and his criticism of corporate America and the US healthcare system.

Kenny said in the NBC interview that Mangione’s family had reported him missing to San Francisco authorities in November.

Associated Press contributed to this story