Ewing: With Perv Busters, are you trying to catch people in the act?

Sliwa: We have, but it’s not the main focus. The predators underground in the subways are creatures of habit. They will ride the same trains at the same times, normally at peak hours, because if a woman objects to him [touching] her or accosting her, he can claim, “Oh, it’s so crowded here, I’m sorry.” We get their photographs, and we begin to hunt them. We have had some arrested, but it’s mostly an informational campaign.

Ewing: Do you ever worry that you’re going after an innocent person?

Sliwa: Of course. The checks and balances are that you don’t act like Donald Trump and retweet something. You do due-diligence forensic research [to see] if you can come up with a name, an identity, other people who will likewise indicate that this person has been molesting women in the area. We’ve been doing this for over a year-and-a-half. We’ve probably leafletted 185 [men]. None of it has come back to haunt us because we didn’t dot the i’s and cross the t’s.

Ewing: How do you do your research?

Sliwa: We try to go online, see if there are other women who likewise have seen this guy, or if he fits a description. A lot of times women will take pictures of these guys—you make sure it’s not Photoshopped. If enough women have come forward and have IDed the guy and he seems to have a certain pattern, then we go with it without police verification.

Ewing: What is enough?

Sliwa: Enough is three or more people who have IDed the guy who aren’t friends with each other and not related—independent sources.

Ewing: Is Perv Busters legal?

Sliwa: It’s legal. But if you ID the wrong person, you yourself can be arrested because, remember, we have no special powers or privileges.

Ewing: Your group started patrolling the subways again in New York City about a year ago—is that right?

Sliwa: No, we have patrolled regularly since 1979. We’ve had patrols every day and every night since we began. But nowhere near to the effect that we had between 1979 and 1993, which is the period that the documentary covers.

Ewing: I read in a Time story that you came back last year because of a series of slashings on the subway.

Sliwa: That’s true. We doubled down, we increased our recruitment, and we began to focus on those neighborhoods that were the feeding system for the slashings. They weren’t taking place all over the subway system, but were in certain key junction areas, particularly up to Harlem, Washington Heights, Inwood, the South Bronx, and parts of Brooklyn. The NYPD didn’t seem to have an answer to it at the time, so we helped to fill the void. [The NYPD did not reply to a request for comment on this story, and the Metropolitan Transportation Authority declined to comment on Sliwa’s campaign in the subways.]

People will get in contact with us if they haven’t gotten relief from first going to the police. We’re always the last choice that a person has when they’re frustrated because they’ve tried all other measures, and they figure they’ve got nothing to lose. The Perv Busters is a classic example: Every time we’re on the subway, we have women coming up, showing us pictures on their cellphones. We always ask, “Did you take it to the police?” They say, “Yeah.” “What happened?” “Nothing.”