The police have issued a fresh appeal for information about the murder of Thomas Devlin in north Belfast.
Thomas Devlin was stabbed as he walked home from a sweet shop
It is six months since the 15-year-old was stabbed to death on the Somerton Road as he walked home with some friends.
Police have said there were a number of people passing through the area at the time who have yet to come forward.
A number of people arrested since the murder have been subsequently released without charge.
Detective Chief Inspector Ian Gilchrist said the investigation was making progress.
"I know that there are people with information, which could help us. They may be people who are very close to the suspects in this case and I imagine they must be really struggling with their conscience," he said.
"We have here the absolutely wanton murder of an innocent schoolboy, taken from his parents, his brother, sister and his friends, denied his life.
"Those people who have knowledge of this murder must do the right thing and contact us; their information is of great importance to this inquiry."
The PSNI have previously said the prime suspects in the inquiry were two young men with a black and white dog.
In January, officers searched empty flats in the Mount Vernon esate in connection with the murder.
Thomas, a student at Belfast Royal Academy, was a talented musician who played the horn at school.
He had just bought sweets from a nearby shop and was on his way home when he was stabbed.
His 18-year-old friend was injured in the attack, but not seriously. A 16-year-old boy managed to escape.