The official was not authorized to publicly discuss details of the ongoing investigation and spoke to The Associated Press on the condition of anonymity.

UnitedHealthcare CEO Brian Thompson, 50, died in a dawn ambush Wednesday as he walked to the company’s annual investor conference at a Hilton hotel in Midtown, blocks from tourist draws like Radio City Music Hall and the Museum of Modern Art.

The words on the ammunition may have been a reference to strategies insurance companies use to try to avoid paying claims.

Investigators recovered several 9 mm shell casings from outside the hotel and a cellphone from the alleyway through which the shooter fled, NYPD Chief of Detectives Joseph Kenny had said earlier.

The killing and the shooter’s movements in the minutes before and afterward were captured on some of the multitudes of security cameras present in that part of the city.

Investigators believe, judging from surveillance video and evidence collected from the scene, that the shooter had at least some prior firearms training and experience with guns and the weapon was equipped with a silencer, the official said.

Investigators are also looking into whether the suspect had pre-positioned a bike as part of an escape plan, the official said. The suspect fled on a bike and he was last seen riding into Central Park.

Authorities were running DNA and fingerprint analysis on items found nearby, including a water bottle, that they believe the suspect may have discarded, the official said.

Security camera video showed the shooter approach Thompson from behind, level his pistol and fire several shots, barely pausing to clear a brief gun jam while the dying health executive tumbled to the pavement.

Other security cameras captured the initial stages of the gunman’s escape. He was seen fleeing the block across a pedestrian plaza, then escaping on the bicycle. Police used drones, helicopters and dogs in an intensive search, but the killer’s whereabouts remained unknown.

Police Commissioner Jessica Tisch said that while investigators had not yet established a motive, the shooting was no random act of violence.

“Many people passed the suspect, but he appeared to wait for his intended target,” Tisch said at a news conference Wednesday.

“From watching the video, it does seem that he’s proficient in the use of firearms as he was able to clear the malfunctions pretty quickly,” Kenny said.

Police issued several surveillance images of the man, who wore a hooded jacket and a mask that concealed most of his face and wouldn’t have attracted attention on a frigid winter day. Some of the photos were taken at a Starbucks coffee shop shortly before the shooting.

The police department offered a reward of up to $10,000 for information leading to an arrest and conviction.

“Brian was a highly respected colleague and friend to all who worked with him,” the insurer’s Minnetonka, Minnesota-based parent company, UnitedHealth Group Inc., said in a statement. “We are working closely with the New York Police Department and ask for your patience and understanding during this difficult time.”

Thompson’s wife, Paulette Thompson, told NBC News that he told her “there were some people that had been threatening him.” She didn’t have details but suggested the threats may have involved issues with insurance coverage.

Eric Werner, the police chief in the Minneapolis suburb where Thompson lived, said his department had not received any reports of threats against the executive.

Investigators also were searching Thompson’s hotel room, interviewing his UnitedHealthcare colleagues and reviewing his social media, Kenny said.

Police initially said the shooter rode into Central Park on a bicycle from the city’s bike-share program, CitiBike. But a spokesperson for the program’s operator, Lyft, said police officials informed the company Wednesday afternoon that the bike was not from the CitiBike fleet.

Health care giant UnitedHealth Group was holding its annual meeting with investors to update Wall Street on the company’s direction and expectations for the coming year. The company ended the conference early in the wake of Thompson’s death.

Thompson, a father of two sons, had been with the company since 2004 and served as CEO for more than three years.

UnitedHealthcare is the largest provider of Medicare Advantage plans in the U.S. and manages health insurance coverage for employers and state and federally funded Medicaid programs.

Minnesota Gov. Tim Walz posted on the social platform X that the state is “sending our prayers to Brian’s family and the UnitedHealthcare team.”

“This is horrifying news and a terrible loss for the business and health care community in Minnesota,” the Democrat wrote.