Just as there is no single form of poverty, there is also no defined set of family patterns or life circumstances that lead to the decisions these women made. There is no formula to explain what brought them to Gilgo Beach. Human trafficking was a factor for one, addiction for another.

But if they shared something, it is that they never disconnected or lived on the street as dictated by the procedural television stereotype. They all stayed close to their families. They all came from towns with narrowing options and were looking for a way out. That’s one way of looking at “The Lost Girls,” the title of my book on this case, which was later made into a movie: They were only “lost” to the extent that we (the police, the media, the social safety net) chose to lose. them, deciding they were worth discarding.

Serial killers understand this, of course. Jack the Ripper targeted the women he sought out for presumably the same reason the Green River Killer and Joel Rifkin said they did: these were women they believed no one would go looking for. And most of the time, sadly, they were right.

Now, 16 years after the disappearance of Ms. Brainard-Barnes, we have an arrest, a suspect: Rex Heuermann, it appears, lived in plain sight, in a Long Island town a short drive from where the bodies were found. He has a spouse and children, and a job with a relatively high profile. In a place as densely populated as New York, he is accused of a double life that seems difficult to contemplate.

His advantage, it seemed, was that no one was looking for him either. In cases involving escort work, the male clients often seem like footnotes, at least to the public. Police locked up Mr. Heuermann just last year, more than a decade after the four bodies were found on Gilgo Beach.

For Mrs. Cann and the other members of the family, it’s an eternity of wondering and waiting, and feeling as discarded as the loved ones they lost.

Robert Kolker is the author of “Lost Girls: An Unsolved American Mystery,” the best-selling nonfiction account of the Gilgo Beach murders.