FBI agent died of cancer after 9/11 Pentagon response. His widow tells his story.

On Sept. 11, 2001, 2,977 people died in the collapse of the twin towers, at the Pentagon or on United Flight 93, which crashed in a Pennsylvania field. But scores of others who worked in the wreckage have died from illnesses in the years since.

At the FBI, more than 400 people have 9/11-related illnesses and at least 33 have died from 9/11-related cancers, according to the bureau.

Sandy and Jack Hess met early on in their careers at the FBI and worked together for years, with Jack focused on counterterrorism after the attacks. Jack retired from the bureau in 2009 to pursue a career in the private sector and often thought about what he saw at the Pentagon that day, according to his wife, but never worried his health might be at risk.

In 2017, what started as a backache became an emergency trip to the hospital, where a doctor found a tumor on his kidney. Sandy was in disbelief.

“I thought, ‘Oh, my gosh, what?’ Like, this is a guy who’s never been sick a day in his life,” she said. Her sit-down with NBC News was the first time she shared their story publicly.

When the doctor asked about Jack’s work history, she recalled saying: “‘Wait, my husband responded to the Pentagon.’ And she looked at me and she said, ‘There has been a huge increase in kidney cancer since 9/11.’”

“Nobody had any kind of protection on. We didn’t even think about it. I mean, it was an emergency situation. We had a mission,” Sandy said. “And people ask all the time if Jack knew he was going to get this cancer, maybe he wouldn’t have gone that day. And I said, ‘You’re absolutely wrong. He would have done it, and he would have been proud, and we’re proud of him. He’s a hero.’”

In 2019, the FBI created a video in which first responders like Jack encouraged others to sign up for health benefits and receive proper medical screenings. In it, Jack said: “It was 17 years ago. I’m fine. I was there for one day. I’m fine. In reality, those were bad assumptions.”

Jack grew increasingly concerned that the effects of that day could threaten the health of his colleagues, even many years later, his wife said.

“Don’t be afraid to go out and get screened and find that something’s wrong with you, whether it’s related to 9/11 or not. Seventeen years is not too long. Eighteen or 19 years probably won’t be too long. You can still get sick from this,” Jack said at the time.

Four years after that plea, he died, surrounded by his wife and four children, who are hoping to carry on his message to others.

“We are not being proactive enough. We just aren’t. People who have responded to 9/11, they need yearly scans,” Sandy said. “Some of this could have been avoided had a scan been done, and maybe, maybe he would have had Stage 2 cancer … but why does he have to wait for a death sentence?”

Specifically, Sandy said that more thorough CT scans — imaging tests that show detailed pictures of the human body — could lead to earlier diagnoses, as opposed to the yearly physicals covered by the FBI. The FBI, for its part, says it continues to encourage first responders to register for the World Trade Center benefits screening program.

As for how she would like him to be remembered, Sandy said her husband “left a legacy of courage, determination and selflessness.”

Now, a quarter of a century after the attacks, it’s not just Sept. 11 that marks a difficult date on the calendar.

“Every holiday is hard. There’s always, always an open seat everywhere you go, so it’s really hard. Father’s Day, the toughest holiday there is. But I try to tell the kids to reflect on all the good times we’ve had and appreciate the time we had with Jack. I had a great marriage for 25 years. Many people don’t have that,” she said.

“He was a father that was hands-on, involved with his kids, and many kids don’t have that, either. And so I try to teach my kids to appreciate what we have, not what we lost.”