New images are released for a 'person of interest' in the CEO's killing in New York

Shell casings with cryptic words were found at the scene of the shooting of Brian Thompson, the CEO of UnitedHealthcare who was killed outside of a Manhattan hotel in New York, police officials say.

The officials confirmed reports that the casings had the words "deny," "defend" and "depose" written on them but did not specify how many shell casing were found, according to NPR member station WNYC's Gothamist. The words are similar to the title of a 2010 book Delay, Deny, Defend: Why Insurance Companies Don't Pay Claims and What You Can Do About It, by Jay M. Feinman.

A manhunt for the shooter is underway as police are trying to piece together details surrounding Thompson's death early Wednesday morning.

A photo of a person interest in the shooting was released by NYPD on Thursday morning.

Here is what we know so far.

The suspect "appeared to wait for his intended target"

The suspect was "lying in wait for several minutes" outside of the New York Hilton Midtown Hotel before Thompson, who was there for an annual investor conference, arrived, NYPD Police Commissioner Jessica Tisch said during a press conference on Wednesday.

As Thompson was walking to enter the hotel, the suspect approached him from behind and fired several rounds, striking him "at least once in the back and at least once in the right calf," Tisch said.

During the shooting the gun jammed several times but the gunman was able to unjam it and continue firing shots, NYPD Chief of Detectives Joseph Kenny said, Gothamist reported.

After the shooting Thompson, the suspect fled the scene on foot through an alley before riding off on a bike, according to Tisch. The suspect was wearing dark clothes and a mask and "appeared to wait for his intended target," Tisch also said.

"A highly respected colleague and friend"

Thompson was 50 years old, a husband and father of two children. He joined UnitedHealth Group in 2004 and held several leadership positions before becoming CEO of UnitedHealthcare in 2021.

Before joining UnitedHealth Group, he was a CPA at PricewaterhouseCoopers, an accounting firm, and a manager in the Transaction Advisory Services group of the audit practice, according to his LinkedIn profile. He received a bachelor's degree in business administration and accounting from the University of Iowa in 1997.

UnitedHealth Group remembered Thompson as "a highly respected colleague and friend to all who worked with him" in a statement on Wednesday.

"We are working closely with the New York Police Department and ask for your patience and understanding during this difficult time," the company said. "Our hearts go out to Brian's family and all who were close to him."

A motive is unclear

The motive for the shooting is still a mystery and police are still searching for the killer. His wife, Paulette Thompson, told NBC News that he was facing threats.

"There had been some threats," she said. "Basically, I don't know, a lack of coverage? I don't know details. I just know that he said there were some people that had been threatening him."

Surveillance video shows the suspect entering Central Park and a cellphone was found in the alley. Every indication in the preliminary investigation is that the shooting of Thompson was a "premeditated, pre-planned targeted attack," Tisch said.

A photo of a person interest in the shooting was released by NYPD on Thursday morning.

NYPD is offering a $10,000 reward for anyone who can provide details about the shooter that could lead to an arrest.

NPR's Rachel Treisman contributed to this report.