The grieving family of a young real estate worker killed in last year’s horrific Midtown mass shooting plans to sue the city for $65 million — claiming police “utterly and completely” failed to stop the crazed gunman before he stormed 345 Park Ave.

The parents and sister of 27-year-old Cornell University graduate Julia Hyman said they were able to view never-before-seen security camera footage showing that NYPD Det. Didarul Islam — who was also slaughtered by the shooter — “bears liability” for her death, according to new court documents.

The video, “which captured the horrific events as they unfolded” on July 28, 2025, allegedly shows the officer, who was working a paid security detail shift at the skyscraper, “standing at the window in the lobby with a clear line of sight of the plaza and the gunman.”

But Islam, a 36-year-old Bangladeshi immigrant, husband and father, allegedly “utterly and completely failed to identify an obvious impending security threat and took no actions whatsoever to thwart or mitigate said threat,” states the petition filed in Manhattan Supreme Court on Thursday.

Gunman Shane Tamura, who had left his home in Las Vegas, Nevada two days earlier and drove to New York City in an apparent bid to target the NFL, exited his double-parked car and crossed an outdoor plaza outside the building while openly brandishing an M4-style rifle.

He then entered a revolving door immediately to the right of Islam, who “took no notice of the gunman, took no actions and offered no resistance whatsoever,” the court papers allege.

“Not a single action by Detective Islam deterred, detected, disrupted, or delayed the gunman’s unimpeded path from the street, up steps, across the plaza, and through the 345 Park Avenue lobby doors,” the filing claims.

“The actions and/or inactions of Detective Islam at the time the assailant crossed the plaza and entered the lobby were negligent and implicate liability” on behalf of the city, the court papers state.

Islam was the first to be shot by Tamura as he entered the building, later dying from his four gunshot wounds in the hospital. The NYPD detectives’ union described his shooting as an “ambush” at the time.

Islam’s family sued Rudin Management, which owns and operates the building, last year for not securing the outdoor plaza. But the Hyman family claims the slain officer and the city bear responsibility for their loved one’s death.

“It became apparent upon viewing the surveillance footage depicting Detective Islam and where he was stationed that the City of New York, by its Police Department, may bear liability for the negligence of Detective Islam for the happening of this tragic occurrence,” the filing states. 

The family, parents Nanci and Greg Hyman and sister Alison Fiedler, negotiated with Rubin to view the footage, which was not filed with the court, according to the petition.

Investigators believe Tamura, 27, aimed to go to the NFL offices in the building but got on the wrong elevator bank instead ended up on the 33rd floor — where he murdered Hyman, who was an associate at Rudin.

“In the moments before being shot, she experienced pre-shooting terror. After being shot, she suffered from intractable pain and the fear of impending death,” the court papers state.

Tamura also shot dead 43-year-old Wesley LePatner, the CEO of a Blackstone real estate investment fund, and Aland Etienne, 46, a security guard at the high-rise.

The city just awarded Islam the NYPD’s Metal of Honor — the department’s highest award — earlier this week.

His widow, Jamila Akhter, accepted the honor on his behalf while carrying their baby, Arham.

The Hyman family argues that because Islam was working as a private security guard as part of the NYPD’s Paid Detail Unit, the city should be found fully liable for the actions of its “rented police officers,” wrote their attorney, Jeff Korek, in the filing.

The petition also notes that the family had to sign a non-disclosure agreement with Rudin in order to view the horrific video.

The family previously hired big-shot attorney Alex Spiro with plans to sue Rudin last year.

Neither Korek nor city officials responded to a request for comment.