On the evening of May 2, 1997, seven-year-old Joe McCafferty went for a sleepover at his aunt’s house, in Huddersfield.
Just hours later, a serious fire broke out at the property after an accelerant was poured through the letterbox of the front door and set alight.
Joe was taken to hospital along with his brother Nicky, but died a short time later.
A new appeal has been launched urging anyone with information to come forward.
The appeal features a new video from Senior Investigating Officer Detective Chief Inspector Damian Roebuck on the street the fire was started.
