The manhunt for a suspect who gunned down a healthcare chief executive in New York is now in its third day, with police chasing several different leads.
UnitedHealthcare boss Brian Thompson, 50, was fatally shot in the back on Wednesday morning outside the Hilton hotel in Midtown Manhattan.
Police say Thompson was targeted in a pre-planned killing, for which they do not yet have a motive.
Investigators are using surveillance photos, bullet casings with cryptic messages written on them, and the suspect’s movements to track him down. They are also working with the FBI and authorities in other states as the search expands beyond New York.
Here’s what we know about the suspect and the investigation.
What lines are police chasing?
Police are working with “a lot of leads”, said former FBI special agent Michael Tabman. On Friday, the FBI offered a $50,000 reward for information leading to an arrest and conviction.
Police have put together more than 200 images of the suspect from his arrival in New York until he fled Midtown Manhattan after shooting Thompson, according to the BBC’s US partner CBS News.
On Thursday they shared two images – the clearest ones so far – of the suspect, one which shows him smiling with his black face mask pulled down.
A hostel receptionist reportedly told police that the photo was taken when she asked him to show his face, in a flirtatious moment.
The man was staying at the hostel on the Upper West Side in New York, where he reportedly used a fake New Jersey license as identification. Police say they have executed a search warrant at the hostel.
Authorities have also been doing a “full sweep” of Central Park – a 2.5 mile (4km) long and 0.5 miles (0.8km) wide area in the heart of the city – and on Friday found a backpack they believe the suspect was carrying at the time of the attack. It has been sent for forensic testing, CBS reports.
Officials are also attempting to make use of DNA evidence, including a water bottle and candy wrapper from the crime scene, as well as a Starbucks coffee cup, that they believe are linked to the suspect.
A mobile phone was also discovered in an alley along the suspect’s escape route.
So far, fingerprints found left behind have been unusable for identification, police said.
What do we know about the suspect’s time in New York?
Authorities have been able to put together an incomplete timeline of his movements in the city, from his arrival on 24 November to when he fled after the attack on 4 December.
New York Police Department (NYPD) Chief of Detectives Joseph Kenny said on Friday that the suspect arrived in the city on a bus that originated from Atlanta, though it’s unclear where he caught the bus along its route.
He then took a cab to the vicinity of the Hilton, the hotel where he would later kill Thompson, and spent about 30 minutes there before heading to the hostel.
At the hostel he had two roommates but neither saw his face as he wore his mask while he was around them, Mr Kenny said.
The suspect left the hostel early on Wednesday, returned to the vicinity of the Hilton and stopped at a Starbucks.
Thompson was shot at around 06:45 EST (11:45 GMT).
At 06:48, the suspect entered Central Park. Shortly before 07:00 he left the park and at 07:04 took a cab to the Port Authority bus terminal.
How did the shooting and escape happen?
The shooting took place in a busy part of Manhattan close to Times Square and Central Park. Thompson had been scheduled to speak at an investor conference later in the day.
According to police, the suspect – who was clad in his mask and light brown or cream-coloured jacket – appeared to be waiting for Thompson for five minutes outside the Hilton hotel where he was expected to speak.
Thompson, who arrived on foot, was shot in the back and leg, and was pronounced dead about half an hour later at a local hospital.
The NYPD said that the suspect’s weapon appeared to jam, but that he was able to quickly fix it and keep shooting.
CCTV footage appears to show the gunman had fitted a suppressor, also known as a silencer, to the weapon.
Investigators reportedly believe the firearm is a BT Station Six 9, a weapon which is marketed as tracing its roots back to pistols used in World War Two.
Police have reportedly visited gun stores in Connecticut to try to determine where the weapon was purchased.
After the shooting, video shows the suspect fleeing the scene on foot. Officials say he later got on an e-bike, which he rode toward Central Park.
Police believe he left New York, possibly on a bus headed for Atlanta, Georgia, sources familiar with the matter have told CBS News.
Atlanta police released a statement on Friday confirming they are helping New York authorities in the investigation.
Three words written on bullet casings
Investigators have so far not identified a motive in the killing, but they are focusing in part on words written in Sharpie on bullet casings discovered at the scene of the crime.
The words “deny”, “defend” and “depose” were discovered on the casings.
Investigators believe this could be a reference to the “three D’s of insurance” – a known reference made by opponents of the industry.
The terms refer to tactics used by insurance companies to refuse payment claims by patients in America’s complicated and mostly privately run healthcare system.
The words resemble – but are not exactly the same as – the title of a book called Delay, Deny, Defend: Why Insurance Companies Don’t Pay Claims and What You Can Do About It.
The book, published in 2010, was written by Jay Feinman, a legal scholar at Rutgers University in New Jersey. It’s billed as an exposé of the insurance industry and a how-to guide for Americans on how to navigate the system.
Professor Feinman declined to comment when the BBC contacted him.
Who was Brian Thompson?
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.
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.
