Two people have been arrested over the disappearance of a teenage boy 21 years ago.
Robert Williams, 15, went missing from his home in Resolven, Neath, on 22 March 2002.
A 59-year-old woman and a 35-year-old man were arrested on Tuesday morning and have since been bailed for further police enquiries.
South Wales Police said Robert attended a house party in Tair Felin, Aberdulais.
The force believes other local people present may hold vital information which could help with its investigation.
Detective Inspector David Butt said: "Robert's mum Cheryl has been updated on these arrests and our thoughts are very much with Robert's family at this difficult time.
"Our priority is supporting them while we work through this new line of inquiry in the investigation."
Earlier this month, Ms Williams issued a renewed appeal to find out what happened to her son.
She said the family needed closure.
"I know that Robert is never coming home," she said.
"I just want his body back so I can bury him. He deserves that. I don't want him out there on his own and we need closure as a family.
"Someone out there knows what happened to him. As a mother knowing my child is lying somewhere has destroyed me emotionally and physically.
"I need to know what happened to him."