The man charged in the shooting death of UnitedHealthcare CEO Brian Thompson was not a client of the health insurer, FOX Business has learned, amid theories he may have targeted the company head over denied claims. 

In an interview Thursday with WNBC-TV, NYPD Chief of Detectives Joseph Kenny said Ivy League graduate Luigi Mangione may have targeted the company because of its size and influence. 

He said a note was found in Mangione's possession when he was detained in Pennsylvania. 

FAMILY OF UNITEDHEALTHCARE CEO SUSPECTED KILLER HAS BIG BUSINESS EMPIRE

"We have no indication that he was ever a client of United Healthcare, but he does make mention that it is the fifth-largest corporation in America, which would make it the largest health care organization in America," Kenny told the news outlet. "So, that's possibly why he targeted that company. He had prior knowledge that the conference was taking place on that date at that location."

Mangione's mother was not a member of UnitedHealthcare either. Kenny noted that Mangione sustained a major back injury in July 2023.

UNITEDHEALTH RESPONDS TO ARREST OF SUSPECT IN CEO KILLING

"It seems that he had an accident that caused him to go to the emergency room back in July of 2023, and that it was a life-changing injury," said Kenny. "He posted X-rays of screws being inserted into his spine. So, the injury that he suffered was, was a life-changing, life-altering injury, and that's what may have put him on this path."

Mangione's family reported him missing to San Francisco authorities in November, Kenny said. 

Mangione is being held in a Pennsylvania jail after his arrest Monday in Altoona. His attorney, Thomas Dickey, has said his client intends to plead not guilty and that he hasn't seen any evidence linking the 26-year-old to the murder. 

Mangione's arrest came days after Thompson was shot and killed on a Manhattan street, followed by a manhunt for the alleged gunman, who authorities say waited outside a hotel where UnitedHealthcare was holding its annual investor conference. 

Shortly after the killing, Mangione took a cab to Washington Heights in Upper Manhattan, near the George Washington Port Authority Bus Terminal, Kenny said. 

GET FOX BUSINESS ON THE GO BY CLICKING HERE

"From there, we have him. We believe he may have taken the subway back to Penn Station and then made his way to Philadelphia from there," the chief told the news station. 

Mangione is fighting attempts to extradite him to New York, where he faces a murder charge.