A 27-year-old standout Cornell grad tragically landed in Shane Tamura’s crosshairs — because the killer accidentally took the wrong elevator to her employer’s floor and encountered her, shooting her dead.

Julia Hyman, who worked for Rudin Management — the company that owns the Midtown skyscraper where Tamura launched his rampage Monday — was one of the four people killed in the horror.

The 2020 Ivy League Dean’s List graduate — who reportedly attended the posh Riverdale Country School in The Bronx when younger and was captain of her varsity high-school lacrosse team — had worked as a Rudin associate for less than a year, according to her LinkedIn.

Investigators believe Tamura wanted to shoot up the NFL’s offices on the building’s lower floors, with him claiming in rambling handwritten notes that he suffered from a brain injury from playing football in high school.

But he ended up in the wrong elevator bank at 345 Park Ave. — and it skipped the NFL’s floors and took him instead up to the 33rd floor, where Rudin’s offices are located and he encountered Hyman.

Three others had been killed in the lobby moments earlier by Tamura: Blackstone exec Wesley LePatner, a married mom of two; NYPD officer Didarul Islam, whose wife is due to soon give birth to their third child; and security guard and dad Aland Etienne.

“The Rudin family and everyone at our company are devastated by yesterday’s senseless tragedy,” a Rudin rep said in a statement.

“Our thoughts and prayers are with those injured and lost last night, including our cherished Rudin colleague, a brave New York City police officer, a beloved lobby security guard and an employee at a tenant firm.”

“We are grateful to the NYPD, FBI, EMS and multiple other emergency responders for their swift and courageous action,” the representative said.

Kate Walsh of the Cornell Peter and Stephanie Nolan School of Hotel Administration, which Hyman attended, called Hyman “an extraordinary student whose academic achievements and intellectual curiosity made a lasting impression.

Follow The Post’s live blog for the latest coverage of the 345 Park Ave. shooting

“Julia’s passion for real estate led her to pursue a minor in the field and build a successful career after graduation,” the professor and dean said.

Hyman’s killer, who drove from Las Vegas to attack the NFL HQ, ended his rampage by fatally shooting himself, cops said.

The crazed shooter left behind notes found stashed in his wallet that claimed he suffered from CTE — the degenerative brain disease that’s been linked to concussions and other repeated head trauma common in contact sports like football.

In the writings, Tamura blamed football for his apparent struggle with CTE and begged for his brain to be studied in the wake of the massacre.

“Please study brain for CTE. I’m sorry. The league knowingly concealed the dangers to our brains to maximize profits,” he wrote. “They failed us.”

How the shooting unfolded

• Reports of the shooting at 345 Park Ave. start coming in around 6:28 p.m.
• Shane Tamura, 27, is seen getting out of a black BMW between 51st and 52nd streets with an M4 rifle.
• He enters the lobby and turns right, where he shoots police officer Didarul Islam, 36, dead.
• Tamura guns down a woman cowering behind a pillar in the lobby, sprays more bullets and walks toward the elevator bank — where he shoots dead a security guard crouching at his desk.
• One more man reports being shot and injured in the lobby. He was in critical but stable condition.
• The gunman allows a woman to walk out of the elevators unharmed before heading up to the 33rd floor, where building owner Rudin Properties’ offices are located, “and begins to walk the floor, firing as he traveled.”
• One woman is shot and killed on that floor before Tamura shoots himself in the chest.
• It’s unclear how long the mayhem lasted. Police Commissioner Jessica Tisch posted on X at 7:52 p.m.: “The scene has been contained and the lone shooter has been neutralized.”

He also name-checked Terry Long, the former Pittsburgh Steelers player who was diagnosed with CTE after downing antifreeze to kill himself 20 years ago.

“Terry Long, football gave me CTE and it caused me to drink a gallon of antifreeze,” Tamura wrote. “You can’t go against the NFL, they’ll squash you.

Mayor Eric Adams confirmed Tuesday that the mentally ill shooter appeared to have been targeting NFL’s corporate headquarters, which has offices in the towering Park Avenue building.

“We’re still going through the suicide note to zero on in the exact reason but at this time it appears as if it’s something attached to his belief he experienced CTE from the NFL,” Adams said in interviews.

Despite suggesting he suffered from CTE from playing in the NFL, Tamura only played high school football in California.