Who killed UnitedHealthcare CEO Brian Thompson? What we know about the suspect on the run

A suspect is on the loose in what police called the "brazen" targeted attack of Brian Thompson, the CEO of major insurance group UnitedHealthcare who was fatally shot outside a Midtown Manhattan hotel ahead of an investor conference on Wednesday.

The masked gunman appeared to be lying in wait outside the Hilton hotel in what police said was a "premeditated" attack. The shooter arrived at the scene about five minutes before Thompson before shooting the victim in the chest around 6:40 a.m., police said.

Video captured the moment the gunman walked up behind the CEO, pointed his gun at him and fired. A witness fled as Thompson stumbled and fell to the ground. The gunman then walked closer to Thompson, firing more times before fleeing.

Evidence recovered includes cellphone, water bottle, candy wrapper

The suspect fled on foot into an alley, where a phone was recovered, according to NYPD Chief of Detectives Joseph Kenny. He then fled on an e-bike and he was last seen riding into Central Park at 6:48 a.m., police said.

Police released photos of the suspect holding a firearm and on a bike. They also released photos of the suspect in a mask, captured at a Starbucks near the hotel before the shooting, according to ABC New York station WABC. He was described by police as wearing a light brown or cream-colored jacket, a black face mask, black and white sneakers and a "very distinctive" gray backpack.

Detectives have also retrieved a water bottle and candy wrapper from the area where he was apparently waiting, law enforcement sources said. After analysis, NYPD investigators believe the cellphone, candy wrapper and water bottle are linked to the shooter, police sources said.

At the same time, NYPD detectives are working with the U.S. Marshals Service to try and track down the shooter and with the FBI, which has the most sophisticated technology for retrieving usable data from cellphones, sources said.

The victim's hotel room has already been accessed by investigators, whose top priority is determining Thompson's most recent conversations and movements, sources said.

Professional killer appears unlikely

The working theory among detectives right now is that the shooting was carried out by someone who is not a professional killer because too many "mistakes" were made, sources said. Hitmen typically don't carry cell phones to their hits and the shots were fired from a distance that would be considered "too far" away from the victim, the sources said.

At this point, detectives are trying to determine whether Thompson was targeted because of some type of personal conflict or as a result of his work as an insurance executive, sources said. The killer apparently had some knowledge of Thompson's schedule on Wednesday and the fact that he would be arriving at the Hilton well before the company meeting was to begin, the sources said.

Police are interviewing Thompson's colleagues and family about any potential specific threats, Kenny said.

What we know about the victim

Thompson, 50, was in New York City for the UnitedHealthcare investors conference, which was scheduled to start at 8 a.m. The conference was being held at the Hilton outside of which he was shot, but he was not staying there, police said.

UnitedHealthcare's parent company, UnitedHealth Group, the largest health insurer in the world, said in a statement, "We are deeply saddened and shocked at the passing of our dear friend and colleague Brian Thompson."

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

Police urge the public to call Crime Stoppers at 1-800-577-TIPS with any information. A $10,000 reward is being offered for information leading to the arrest and conviction of the person responsible.