The Isabella Stewart Gardner Museum’s security director, Anthony Amore, is never far from his work searching for the 13 missing pieces of art lifted from the museum a quarter century ago.

"In my wallet, I keep a reminder for myself, along with pictures of my children; it’s an actual-size replica of the Rembrandt self-portrait etching that was stolen in 1990," he said, "and it always reminds me when I’m getting my money out or too often to get my phone that there is a job that remains to be done."

Amore joined the museum 15 years after what remains the biggest art heist in American history. Consumed with the theft, the onetime homeland security agent wears his intensity on his sleeve.  

"I think it's impossible not to be obsessed," he said.

Most of what Amore knows about the case and ongoing investigation he cannot share. But he said the museum receives eight to 10 tips weekly, he speaks with the FBI daily, and every lead is pursued. 

"I'll use of football analogy: it's like being in the red zone," he said. "You marched down the field all the way to the opponents, basically their goal line, driving the ball home as Seahawks found out football at the Super Bowl, is where it gets even more difficult. And that's how I feel where we are now; I believe that we're at that point the hard work remains to be done."

It’s now been 25 years since the theft. It’s a long time Amore says, which can also go a long way.

"The scariest people involved might have died off or wives become ex-wives—that old saying," he said. "Of course, I mean, I'd be lying if I didn't say that when a quarter-century passes, people die, and it’s a little more difficult to get accurate recollections and such and that's where the hard work comes in. Talking to everyone we can talk to."

Longtime Gardner Museum Director Anne Hawley recounted the aftermath of the heist.

Two years ago, the FBI announced it knew the identity of the thieves. While a surprise revelation, it failed to bring back the art. But Amore said the tips it generated did prove helpful.

"Since the press conference, the ones of that have come in have been more, I'd say, direct or targeted towards what we are looking for."

Like many, Amore fully expects the stolen art to return one day. Until then, he says, it gnaws at him. 

"I have to parse my words because I don’t want people to think I'm crazy," Amore said, "but I often will go into the galleries at night sit there in the dark, and picture what it was like the night the theft happened, the soft lights on. It’s a constant reminder to me that there's a job to be done, and at the same time, though, it’s a constant message to the public that we are going to get them back and we haven’t forgotten them."

Catch up with our ongoing coverage of the investigation.