What a new photo reveals about the shooter in CEO Brian Thompson killing

Police in New York are using facial recognition technology and a discarded mobile phone to track down the killer of a healthcare chief executive.

UnitedHealthcare boss Brian Thompson, 50, was fatally shot in the back on Wednesday morning outside the Hilton hotel in Midtown Manhattan.

The attacker fled the scene without taking any of Thompson's belongings. Police believe the victim was targeted in a pre-planned killing.

They are focusing on a surveillance image taken in a branch of Starbucks just before the shooting.

Here's what we know about the suspect and the investigation.

So far, the investigation into Thompson's killing has centred on a few clues that police are using to identify the suspect.

Police revealed the suspect was photographed at a nearby Starbucks just minutes before the shooting.

While he is masked in the image, police sources told CBS that the mask is pulled down far enough so that his eyes and part of his nose can be seen.

With that, investigators are using facial recognition software to try to find a match.

Additionally, police are testing three bullet casings and three live rounds found at the scene for DNA.

The words "deny," "defend" and "depose" were discovered on the casings, according to US media reports.

A mobile phone was discovered in an alley along the suspect's escape route. Police say they are "working through" the phone.

Investigators also said they would search Thompson's room at the nearby Marriott, which is down the street from where the incident took place.

Thompson joined UnitedHealth, the biggest private insurer in the US, from accountancy firm PricewaterhouseCoopers in 2004.

He rose through the ranks and became CEO in 2021, leading the company through some very profitable years.

Investigators have so far not identified a motive in the killing, although police did note that the assailant fled without taking any of Thompson's belongings.

In an interview with MSNBC, Thompson's wife said that there had "been some threats" against him earlier, although she was unable to provide details.

"I just know that he said there were some people that had been threatening him," she said.

According to police in Thompson's hometown of Maple Grove, Minnesota, there had previously been one suspicious incident at his home in 2018.

The incident was cleared with no criminal activity detected. No additional details were provided.