What we know so far about UnitedHealthcare CEO’s fatal shooting and the manhunt for the suspect

Police continue to comb through evidence and search for clues more than 48 hours after a masked shooter gunned down UnitedHealthcare CEO Brian Thompson outside of a midtown Manhattan hotel.

Detectives have located a water bottle possibly discarded by the shooter, collected shell casings with cryptic words written on them, and released photos of the person they believe is the gunman. But the shooter’s identity, whereabouts and motive remain a mystery.

Here’s everything we know about the Wednesday morning shooting.

Gunman was ‘lying in wait for several minutes’

Thompson, dressed in a suit, was on his way to UnitedHealth Group’s investor conference around 6:45 a.m. Wednesday when a gunman approached him from behind and shot him at least once in the back and at least once in the right calf outside of the New York Hilton Midtown hotel.

Security video showed Thompson stumbling forward after the first shot as a person standing nearby ran to safety. The shooter, walking toward Thompson, cleared a jam in the gun before continuing to fire, the video showed. Thompson fell to the ground and the shooter fled on foot before mounting an electric bike.

Police said the gunman was wearing a black hoodie and black pants and carrying a gray backpack. It is believed he used a firearm with a silencer, a person familiar with the matter told CNBC.

Thompson, 50, was pronounced dead at Mount Sinai West.

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

The shooter was “lying in wait for several minutes,” she said, calling it a “premeditated, preplanned targeted attack.”

NYPD Chief of Detectives Joseph Kenny told reporters that the gunman arrived at the scene about five minutes before the shooting.

Thompson received threats before his death, wife says

Paulette Thompson told NBC News on Wednesday that her husband had been receiving threats but she was unclear of their nature.

“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.”

Police in Thompson’s hometown of Maple Grove, Minnesota, said they had not been notified of any threats against him, Commander Jonathan Wetternach said Wednesday.

Despite the threats, Thompson did not travel with security.

“Speaking to other employees that traveled with him to New York, it doesn’t seem like he had a security detail,” Kenny told reporters. “He left the hotel by himself, was walking, didn’t seem like he had any issues at all.”

No current or former executives of UnitedHealth Group receive regular company-funded personal security service, according to the insurance giant’s two most recent proxy statements. Companies have to report security expenses for corporate officers or directors if the value exceeds $10,000 per year.

Former FBI supervisor Rob D’Amico said he believes Thompson’s death has all the makings of a personal vendetta tied to his company.

Thompson’s family said they are “shattered to hear about the senseless killing of our beloved Brian.”

“Brian was an incredibly loving, generous, talented man who truly lived life to the fullest and touched so many lives,” the family said in a statement obtained by NBC affiliate KARE of Minneapolis.

‘Deny,’ ‘defend’ and ‘depose’ written on ammunition

Shell casings found at the scene had the words “deny,” “defend” and “depose” written on them, a senior New York City law enforcement official briefed on the investigation told NBC News on Thursday.

It’s not yet known if the messages could indicate a motive.

“The motive for this murder is currently unknown, but based on the evidence we have so far, it does appear the victim was specifically targeted,” Kenny, the NYPD Chief of Detectives, said at Wednesday’s news conference. “But at this point, we do not know why.”

Police also recovered a cellphone near the scene.

Who is the shooter?

The gunman remains at large but investigators have been able to gather some information about him.

Police believe he may have traveled to New York City last month by Greyhound bus, three senior law enforcement officials familiar with the case told NBC News. The bus left from Atlanta.

Officials are looking into whether they can find a name used for the Nov. 24 trip. Greyhound has said it is cooperating with authorities on the investigation.

While in New York, the shooter stayed at a hostel on the Upper West Side of Manhattan. Police are looking into whether the gunman paid in cash and used a fake ID to rent a room, according to two law enforcement officials briefed on the investigation.

Police were able to obtain an unmasked picture of the gunman smiling while at the hostel.

Footage was released that may show the gunman exiting a subway station about half an hour before the shooting. Investigators also learned that he visited a Starbucks before the shooting and purchased a water bottle and two protein bars, according to a senior New York City law enforcement official briefed on the investigation.

Detectives recovered a video showing where he discarded the items, and police collected them as evidence, hoping it could aid in the investigation, the official said.

Following the shooting, the gunman fled on foot and then mounted an electric bike, the police commissioner said Wednesday. He was last seen in Central Park.

Crime Stoppers is offering a $10,000 reward for information.