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Paul Mauro, a retired NYPD inspector, retraced the shooter’s steps before and after the killing of UnitedHealthcare CEO Brian Thompson on a New York City street earlier this week.

“The shooter knew where to go before and after,” Mauro said, meaning he planned the fatal attack and may have retraced the route he took the morning of the murder and did some “reconnaissance.”

The suspected first shooter was seen at a Starbucks in midtown Manhattan and went to the scene of the shooting. Mauro said he didn’t have the bike he was seen with after the shooting.

“There’s a bike waiting for him somewhere in here that he’ll purchase after the event,” Mauro said.

When he arrived in an alley where he was believed to be walking near the West 54th Street shooting, he still didn’t have a bike that could have been hidden anywhere nearby, Mauro said.

Just before he opens fire, the gunman waits nearby for Thompson before firing, apparently jamming the gun. Three empty cartridge cases with notorious messages and three live cartridges were found at the crime scene.

After the shooting, the shooter comes back through the alley from which he came.

“The bike was hidden somewhere back there,” Mauro said. “We don’t know how and by whom.”

As the shooter exited the alley, he dropped his burner phone.

“He almost certainly went that way and did some reconnaissance before he fired,” Mauro said.

He added that investigators will most likely review camera footage from the area in the days before the shooting to see if he scouted the area. The masked gunman arrived in the city several days before the murder.

After the killing, the suspected shooter rode his bicycle toward Central Park.

“This is kind of a moment where he stays in the dark from the police and the cameras until he leaves the park on the Upper West Side,” Mauro said. “He was in that park probably within two or three minutes and from then on and…” With the size of that park, it’s a needle in a haystack.”

Julia Bonavita of Fox News Digital contributed to this story.