A woman whose childhood friend was abducted 31 years ago at the age of nine has made a documentary charting her search for him, to be premiered on Tuesday in the US city of Boston.
The film includes haunting witness accounts of Andy Puglisi's abduction
Have You Seen Andy? investigates the disappearance in the summer of 1976 of Andy Puglisi at a swimming pool in Lawrence, Massachusetts.
Although a body has never been found, the film reaches the grim conclusion that the likeliest explanation is that Andy was snatched and killed by a small gang of paedophiles who had been at the pool.
The film's director is Melanie Perkins - a close friend of Andy. She told BBC World Service's The World Today programme that after the search was called off, she remembered thinking "when I grow up, I'm going to find him."
In 1998, 22 years after he vanished, she began her search - filming as she went along.
"Being nine years old and having a childhood friend just vanish into thin air would stay with anyone - and Andy was such a sweet and kind little boy," she said.
"I had a big crush on him that summer, and he disappeared, and our whole world changed."
Fifty-eight thousand children are abducted in America every year. Of those, 115 on average are never seen again.
Ms Perkins, who described her search for her childhood friend as a "strange and powerful journey", said she was struck by talking to the other children, now mature adults, who had been affected when she went back to Lawrence.
Experts put together an image of how Andy might have aged
"Bar none, every single child - now in their 40s - was as deeply affected by Andy's abduction as I was," she said.
"It's changed our parenting - we all have fears and anxieties that other children who didn't go through a similar experience don't have. We were all very much affected by Andy's disappearance, even 30 years later."
But she also said that her search had turned up a number of unpleasant characters.
"We knew there were five paedophiles at the pool that day - the police told us that," she said.
"One of the paedophiles comes out as a very strong suspect in Andy's abduction, and I felt that the circumstantial evidence was so strong as to what happened to Andy that day that, frankly, he was abducted by a serial sex offender.
"I believe that more than likely Andy's body is still in the area."
Ms Perkins also outlined parallels between Andy Puglisi and the current case of the missing British girl Madeleine McCann, who was taken from her hotel room in the Algarve.
"A lot has changed, but a lot of things have stayed the same - and one of the things that's universal is the pain of losing a child," she said.
"I remember, when Andy disappeared, a lot of people initially wanted to blame the family - and you see in the film that the police focused on the family for a long time.
"I think that sometimes society or the public does that to protect themselves from the horror of what can actually happen to a child, and to think that maybe it could happen to them.
Perkins was one of Andy's closest friends in childhood
"They think the family did wrong, or that there must be some reason that what happened took place. I don't think that's always the case."
She added that she had been watching television news nightly after the disappearance of Madeleine.
"I think so much about her little cousins, and little neighbourhood friends, and all those children in her life that are going to be really affected and traumatised for the rest of their lives by what happened to her," she added.
"I think that people don't realise that when one child is missing, so many children are affected."