Two men have been arrested over the disappearance of a teenage boy 15 years ago.
Andrew Gosden, then aged 14, travelled from his hometown of Doncaster to London by train on 14 September 2007 and was caught on CCTV arriving at King's Cross station.
What happened to him afterwards has proved a mystery, and no information about his movements has been corroborated by police.
But South Yorkshire Police have revealed a 45-year-old man was arrested on 8 December on suspicion of kidnap, human trafficking and possessing indecent images of children.
A 38-year-old man was detained on the same day on suspicion of kidnap and human trafficking.
The pair, who are both from London, have now been released under investigation while inquiries continue.
Andrew Gosden would now be 28 years old.
Senior investigating officer, Detective Inspector Andy Knowles, said: "Our priority at this time is supporting Andrew's family while we work through this new line of enquiry in the investigation.
"We are in close contact with them and they ask that their privacy is respected as our investigation continues.
"We have made numerous appeals over the years to find out where Andrew is and what happened to him when he disappeared.
"I would encourage anyone with any information they have not yet reported to come forward."