I have the impression that this child was kidnapped on the beach or perhaps he saw someone he knew and he betrayed him but he is alive, I don't think this has been many years and these are the same ones that his family has been looking for him...
rest in peace
It does seem possible that he was kidnapped for sure. He'd been to a community carnival the night before with friends and had missed his curfew, prompting his father to pick him up. He was scolded for it, but the scolding doesn't seem to harsh based on how his own mother recounts the story in her book: Vanished: What Happened To My Son by Shirley Brown (which is available as an e-book for a small fee on Amazon).
I've never been able to determine anything further about the carnival such as who he went with, or which company hosted the fair. Was this a carnival with rides and games or was it just a petting zoo type thing? I've no idea. It would be interesting to know whether it was a travelling carnival with workers who may have set up camp, stayed in trailers and then left town at the end of the event? How long were they there for? Were the workers (and or volunteers) interviewed by police?
Per the same account by his mother, she wrote that he left her company at about 4pm. He was to go home and do his paper route, which had 6 houses. He originally was going to go return to meet her at the camp where she was working, but then changed his mind and noted he would stay home after doing his papers. It seems he never got to his papers as his father found them undelivered when Robbie's absence was noticed around 6:30pm that evening. His father and brother ended up delivering the papers for him.
Police found a witness at the beach, a parking attendant who said she'd seen Robbie at 4:15pm. Apparently she had a conversation with him and went to help a customer. On her return, he was gone. I don't know who the witness was or how she was sure it was Robbie that she'd spoken with. No idea how long after police spoke with her or if any other witnesses were found that day (again, all from Shirley Brown's book).
We know from the same book that Robbie's little brother Michael had seen him walking along the road and had waved to him as he passed by in the car of a family friend. It does seem clear he at least made it back to the beach that day after parting ways with his mother.
So was he there to meet someone in particular? It seems that perhaps he was to me. If he was dragged away kicking and screaming, surely there would have been witnesses. But he wasn't. He quietly vanished and no one seems to know where to, or why. I do not believe as some do that he went back to the beach to swim. There were no clothes belonging to him found in the area, and he had been wearing clothes over his swimming attire, so surely they'd have found something if he'd taken them off to dip in the lake. I'd love to know who the parking attendant witness was and pick her brains about what she saw. Anyone she noticed or how things seemed to her at the time - they must have seemed fairly average because it doesn't seem anything set off alarm bells enough for us to know about it. I'd like to meet with whoever his friends were as well. Who did he go to the carnival with? What did they know or suspect might have happened to Robbie?