Police are making further enquiries into the murder of Vishal Mehrotra, who was eight when he was abducted from a London street in 1981.
His remains were found seven months later in woodland in Rogate, Sussex.
No one has been convicted of his murder.
Vishal was walking home from the shop when he vanished on the day of the royal wedding of Prince Charles and Princess Diana.
Detectives visited Vishal’s father on Wednesday to reassure him “all viable lines of enquiry, including from any recent media coverage, will be pursued”, Sussex Police said.
Further enquiries are being carried out by the Surrey and Sussex Major Crime Team after a Channel 4 documentary and BBC podcast unearthed new evidence about the case.
Police also apologised for failing to spot a potential link between Vishal’s murder and a document found in the possession of a convicted paedophile.
The document was titled “Vishal” and was found in 1996 as part of an investigation into historic child sexual abuse at Muntham House School in West Sussex.
It was investigated in relation to sexual abuse at the school but the possible connection with Vishal’s murder was not made until 2019, during the independent inquiry into child sexual abuse.
Detective Superintendent Mark Chapman said police were “committed to identifying those responsible for Vishal’s tragic death and to delivering justice for Vishal and his family”.
“We acknowledge the ongoing distress to Mr Mehrotra and Vishal’s wider family and their need to find answers to what happened to Vishal in 1981.”
He said officers will continue to follow up on any reasonable and viable lines of enquiry and welcome any new information.
Anyone with information relating to the case is urged to get in touch with police online.
