"CBS This Morning" senior correspondent John Miller, a former FBI Assistant Director, was a local reporter in New York City and covered the story when Etan Patz disappeared
Etan Patz has the tragic distinction of being the first missing child ever shown on a milk carton.
His disappearance in New York City captivated the nation in 1979, and the mystery has never been solved.
But now, the New York Police Department and FBI were to begin digging up the concrete floor in the basement in a Manhattan building just down the street from the last place Patz was seen -- the school bus stop.
"We are putting greater emphasis on this location, looking forensically for any evidence of human remains of clothing," says NYPD spokesperson Paul Browne.
Authorities are cautiously optimistic the search will succeed.
Sources tell CBS News cadaver dogs had indicated the presence of human remains during a search there several days ago.
The day before Etan vanished, he came home with a dollar from Othniel Miller, now 76, a neighborhood handyman who used to pay Etan when he helped with small chores. Miller had a workshop in the basement now being searched. Just after Etan disappeared, a new concrete floor was put down.
"The FBI's been here to investigate the case," says Stephanie Miller, his daughter. "He cooperated with them, went to the site, and he doesn't have anything to do with it."
Perhaps because the boy's father was a professional photographer and had hundreds of clear images of a blonde-haired boy with an impish grin, perhaps because the case tapped into every parent's nightmare, the disappearance haunted the nation.
"You see his face," says Lisa Cohen, author of "After Etan." "You see those blue eyes. You see a beautiful innocent boy, and someone who never had a future."
Images of Etan Patz were placed in milk cartons and started the movement that led to the founding of the National Center for Missing and Exploited Children.
But for Stan and Julie Patz, there was never closure.
In 2000, they spoke with "60 Minutes" about their refusal to give up hope.
"We have his belongings all over the house," Julie Patz said. "To put them away, it seems to, to us and to our children that he's gone and he's not coming back."
To date, no one has ever been charged in the case, but many suspected Etan was kidnapped and murdered by Jose Ramos, a friend of Patz's babysitter who is in jail on child molestation charges in Pennsylvania.
Now, authorities are looking at new leads that may point to other suspects.
Investigators are cautiously optimistic the renewed search will lead to Etan's remains because of the interviews they've had with Othniel Miller, and because the dog alerted them to that basement, and because of the odd circumstances of when that concrete floor was laid after Etan's disappearance.
To see John Miller's report, click on the video in the player above.