More than 48 hours after a masked gunman shot and killed UnitedHealthcare CEO Brian Thompson in front of a midtown Manhattan hotel, police continued to review evidence and search for clues Friday.
Detectives found a water bottle that may have been discarded by the gunman, collected shell casings with cryptic words written on them, and released a photo of the suspected gunman. However, the identity, location and motive of the gunman remain a mystery.
Here’s everything we know about Wednesday morning’s shooting.
The gunman “stayed in ambush for several minutes”
Mr. Thompson, wearing a suit, was on his way to speak at a UnitedHealth Group investor conference around 6:45 a.m. Wednesday when a man with a gun approached him from behind and shot him at least once in the back and on the outside of his right calf. Shot at least once. Hilton Midtown Hotel in New York.
Security video showed Thompson staggering forward after the first shots were fired as bystanders ran to safety. Video shows the gunman unclog his gun as he walks towards Thompson and then continues firing. Thompson fell and the suspect fled on foot on an electric bicycle.
Police said the suspect was wearing a black hoodie, black pants, and was carrying a gray backpack. A person familiar with the matter told CNBC that the suspect appears to have used a gun equipped with a silencer.

Thompson, 50, was pronounced dead at Mount Sinai West.
“A number of people passed the suspect, but it appeared the suspect was waiting for his intended target,” New York Police Department Commissioner Jessica Tisch said Wednesday.
He said the gunman had been “waiting for several minutes” and called it a “premeditated, pre-planned, targeted attack.”
NYPD Chief of Detectives Joseph Kenney said the gunman arrived on the scene about five minutes before the shooting.
Thompson’s wife says he received threats before he died
Paulette Thompson told NBC News on Wednesday that her husband had received threats, but she didn’t know what they were about.
“There were some threats,” she said. “Basically I don’t know. Was it because there wasn’t enough coverage? I don’t know the details. All I know is that he said there were some people who were threatening him.”
Police in Thompson’s hometown of Maple Grove, Minn., have not been notified of any threats against Thompson, Commander Jonathan Weternach said Wednesday.
Despite the threats, Thompson did not travel to safety.
“In speaking with other employees who accompanied him to New York, it did not appear that he had a security detail,” Kenney told reporters. “He was walking out of the hotel by himself and didn’t seem to have any problems.”
UnitedHealth Group’s current and former executives do not receive regular company-funded personal security services, according to the company’s two recent proxy statements. Companies must report security costs for officers or directors that exceed $10,000 per year.
Former FBI Supervisor Rob D’Amico said he believes Thompson’s death was all about personal vendettas connected to his company.

Thompson’s family said they were “devastated to learn of the senseless killing of our beloved Brian.”
In a statement obtained by NBC affiliate KARE in Minneapolis, the family said: “Brian was an incredibly loving, generous and talented man who truly lived life to the fullest and touched so many lives. I gave it,” he said.
The words “denied,” “defense,” and “abandonment” are written on the ammunition.
Shell casings found at the scene had the words “deny,” “defense” and “discard” written on them, a senior New York City police official briefed on the investigation said Thursday.
It is still unclear whether the messages may indicate a motive.
“Based on the evidence we have so far, it appears that the victim was specifically targeted,” NYPD Chief of Detectives Kenney said earlier this week. “But at this point we don’t know why.”
Police also recovered a mobile phone near the scene.
Who is the shooter?
The suspect remains at large, but investigators were able to gather some information about him.
Police believe he may have traveled to New York City on a Greyhound bus last month, three law enforcement officials familiar with the case told NBC News. The bus departed from Atlanta.
New York authorities are investigating whether they can find the name used for the Nov. 24 trip. Greyhound said it is cooperating with authorities in the investigation. Atlanta police officials said Friday they have been contacted by the NYPD and will provide assistance if needed.
While in New York, the suspect stayed at a hostel on Manhattan’s Upper West Side. Police are investigating whether the gunman paid in cash and rented a room using false identification, two law enforcement officials briefed on the investigation said.
Police were able to obtain a photo of the gunman without a mask, smiling at the hostel.

A video was released showing the gunman leaving the subway station about 30 minutes before the shooting. Investigators also determined that the man had visited a Starbucks before the shooting and purchased a water bottle and two protein bars, according to a New York City police official.
The official said detectives found a video showing where the items were dumped, which police collected as evidence in hopes of aiding the investigation.
The police chief said Wednesday that after the shooting, the gunman fled on foot and then on an electric bicycle. He was last seen in Central Park.
Crime Stoppers is offering a $10,000 reward for information.