When I hit a few of the first games at the new Yankee Stadium and CitiField, something seemed a little off—and it wasn’t just that I could get military-grade BBQ and sushi if I so chose. No, what threw me were the wandering troupes of what I presumed to be security officials, who looked and acted like something out of a covert-ops installation. Think black outfits and walkie-talkies.

During breaks in game action, they’d mosey down to the lip of the field and collect any number of items—bats, bases, you name it—and just as quickly disappear back into the crowd. They were particularly concentrated right behind the fences in left and right field.

Curious baseball dingbat that I am, I inquired about these mysterious individuals. My journamalistic instincts eventually led me to Howie Shelton, who oversees MLB’s Authentication Program.

The dudes at the game, it turns out, were battle-tested authenticators, charged with making sure that items sold to fans and collectors are legit. Their job, in a nutshell, is to affirm that the game-used Brad Ausmus chest protector that you’ve had your heart set on is actually a game-used Brad Ausmus chest protector, as opposed to one used by a faceless bullpen catcher. Once the authenticators attest that an item is, indeed, authentic, they slap an un-tamper-with-able (Is that a word? It is now) hologram on it and move on to the next piece of memorabilia.

Howie’s a cool dude. Here’s what he had to say about the authentication police and the program.

How does this thing work?
Technically, Major League Baseball isn’t doing the authentication – it’s a third-party organization that we hired. The people doing the authenticating are law-enforcement officials. They’re at every game, all 2,030 of them, every season.

How can I apply for the job?
(Laughs) There’s no application process. Baseball has a longstanding security program and the security guys are local police officers. The thinking was to hire more people like that and train them to be authenticators. They have to have a certain rank within law enforcement, as well as some kind of relationship with the club whose games they’re working. There’s an average of four of them for each team.

How do they know what to look for?
We send out lists, plus they receive information from the PR department of every club. They also have the press notes. They’re aware before the game that we’re looking for certain items—“hey, Jim Thome is going for home run number such-and-such, be on the lookout for that.” We overcommunicate. I’ll send the same note three or four times.

How’d the authentication program get started? Why does baseball need something like this?
It was the FBI investigation, “Operation Bullpen.” They determined that around 75 percent of all memorabilia in sports and entertainment were forgeries, and baseball is something like 75 or 80 percent of the memorabilia market. We’d lose our bond and trust with the fans if they got fake merchandise.

It was really small at first. I think we authenticated 100 items that first year, but we’re up to almost three million over the course of the program. Last year, we did 500,000 items.

How do players and coaches respond when you ask them to sign something or pose for a picture?
Most of the authentication we do happens during spring training. It’s a way to get these guys to sign for the whole season in a relaxed atmosphere. A club like the White Sox did almost 10,000 items during a three-week period in spring training. They want to get it out of the way. During season, there’s maybe a couple of baseballs or bases.

What’s the strangest item that’s been authenticated during your time on the job?
Remember the AL Division Series in 2007, when the gnats and bugs attacked Joba Chamberlain in Cleveland? We authenticated the can of bug spray from that game. Sports Illustrated said that was a sign that the apocalypse is upon us (laughs). We also do game-used dirt—we clean it up and call it “game-used soil.” Last year, during the last games at Yankee Stadium and Shea Stadium, they had buckets set up at every position. They got shortstop dirt, third base dirt, you name it.