Timeline of events leading to the fatal shooting of UnitedHealthcare CEO, Brian Thompson, outside Midtown Hilton hotel

The CEO of UnitedHealthcare was killed by a gunman in a targeted attack outside a Manhattan hotel where the health insurer was hosting its investor conference, police confirmed. The assailant fled the scene, prompting a widespread search.

Police say 50-year-old Brian Thompson was shot around 6:45 a.m. outside the New York Hilton Midtown.

MORE: Who was Brian Thompson, the UnitedHealthcare CEO fatally shot in NYC

ABC News has been piecing together what led up to the shooting as investigators work to figure out what happened.

Here’s a timeline of events:

The exact timing before the shooting remains unclear
Law enforcement sources disclosed to ABC News that the suspected shooter arrived in New York last month on a bus from Atlanta.

Police sources said he went through Port Authority Bus Terminal and detectives are looking to see if they can spot him on video.

The suspected shooter checked into the HI New York City Hostel on the Upper West Side using a fake New Jersey license on November 30, according to police sources. Detectives are analyzing video footage to track his movements leading up to the incident.

On Thursday, police released the first images of the suspect’s face uncovered taken from surveillance video from inside the hostel.

Police were able to find an image of the suspect without his face mask because he was flirting with the woman who checked him into the hostel, police sources told ABC News.

As he stood at the check-in desk, the sources said the woman asked to see his smile. The shooter obliged, pulling down his mask long enough for the surveillance camera to capture his face.

After the shooting, the NYPD obtained a warrant to search the hostel.

Wednesday, 5 a.m.
The suspected shooter was seen on video outside the nearby Frederick Douglass Houses public housing project, carrying what appears to be an e-bike battery, police sources told ABC News.

6:15 a.m.
Surveillance footage reviewed by police shows someone who appears to be the suspect exiting the subway before the shooting at the 57th Street station on the F line, just blocks from the shooting scene.

Before the shooting
Sometime before the shooting, the suspect is spotted at a Starbucks. The exact time is not clear.

Around 6:39 a.m.
According to investigators, the suspected shooter arrived at the scene about five minutes prior to Thompson.

“It appears the suspect was lying in wait for several minutes,” NYPD Commissioner Jessica Tisch said during a briefing Wednesday morning. “Many people passed the suspect but he appeared to wait for his intended target.”

6:44 a.m.
The victim was seen on video leaving a hotel across the street where he was staying and walking towards the Hilton.

“The shooter steps onto the sidewalk from behind a car… approaches the victim from behind, and shoots him in the back. The shooter then walks toward the victim and continues to shoot. It appears that the gun malfunctions, as he clears the jam and begins to fire again,” NYPD Chief of Detectives Joseph Kenny said.

Thompson was struck in the back and the leg.

The suspected shooter then fled, first on foot into an alley.

He was later seen riding an electric bicycle north on Avenue of the Americas.

6:46 a.m.
“Patrol officers from Midtown North precinct responded to a 911 call of a person shot in front of the Hilton hotel,” Kenny said.

6:48 a.m.
The officers found Thompson on the sidewalk and he was later removed by EMS to Roosevelt Hospital.

In the same minute, the suspected shooter was seen riding into Central Park at Center Drive.

6:59 a.m.
Video obtained by ABC News shows the suspected shooter riding west on West 85th Street.

7:12 a.m.
Thompson was pronounced dead at the hospital.

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