A 17-year-old Belgian boy was stabbed to death for his iPod last week.

The crime led to a storm of protest in the country's capital, Brussels, where 10,000 people marched to express their grief and anger at the murder of Joe Van Holsbeeck.

The killers haven't been apprehended – even though the stabbing took place in the ticket hall of Brussels' central station in mid-afternoon. Thousands of commuters were in the area as the boy was stabbed several times by his assailants. He later died in hospital of his wounds.

However, closed circuit TV footage of the attackers has been released, and the victim's family and supporters have raised an urgent appeal for information from people who may recognise them.

You can see still images taken from the CCTV footage here.

Belgium's Catholic Cardinal Godfried Danneels asked why bystanders allowed the crime to take place, saying: "Where were the watchers and guardians, where were we?"