WASHINGTON — It was a day that changed the lives of every American. It shook our sense of security.

It triggered a military conflict on the other side of the globe. And it created a generation of first responders, forever scarred by what they saw. 

Eighteen years later, on the 9/11 anniversary, one married couple is retiring from the FBI together, to honor those that died. 

"Surreal was the only way to put it," Tom O'Connor said. 

O'Connor joined WUSA9 at the Law Enforcement Memorial, along with his wife Jean, also an FBI agent. The duo have served their country as members of the FBI for a combined 43 years. 

"I had not seen anything like that," said Jean. "Except in the movies." 

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Tom responded to the Pentagon within 15 minutes of the attack. Jean would join him about 45 minutes later. The duo said it was not an exaggeration to say that these horrific events transformed their careers and lives. Now, 18 years later, it's a fitting end for the O'Connors. In many ways 9/11 defined their careers. Now it would mark that journey's end. 

Tom and Jean O'Connor at the Pentagon on 9/11
Tom and Jean O'Connor at the Pentagon on 9/11
Tom and Jean O'Connor

"We want to pay honor to our friends who never had the opportunity to retire," said Jean. "And it's our way of giving closure."

Tom, who is also stepping down from his position as president of the FBI Agent Association, said that it's about remembering those lost both in the attacks, and in the time since. Thousands have become sick, and hundreds have died, from illnesses caused by the toxins breathed in during the attacks. 

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"Many of our friends," he said. "People we worked with every single day, people who sat next to you, are no longer here. They can't retire. So we are not going into retirement saying 'this is awful that we have to retire.' It's awesome that we get to retire." 

Tom and Jean O'Connor Walking Together By White House
Tom and Jean O'Connor Walking Together By White House
Tom and Jean O'Connor

As they move forward though, the memory of that day remains with them. Jean gestured toward a necklace she was wearing, as she spoke. On one side of the necklace was the Pentagon, and on the other was the World Trade Center. 

"I look at it every day," she said. "I don't take it off very often. Every once in awhile. I do think about it every day." 

At the time of the attack, Jean was on a drug squad, but would soon change her focus toward terrorism. As for Tom, he's been on the same terrorism response team for 22 years, which he said was "pretty much unheard of," within the FBI. Tom said his motivation for coming into work was clear every single day; Avoiding this type of heartbreak in the future. 

"This is not happening again," he said. "If there's anything we can do to not go through that. And to have the families - every day and every night you think about that."

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