The boy, believed to be five or six years old, was found wrapped in foil and weighed down with a flagstone slab in the River Danube, near Grossmehring, a Bavarian municipality 80km from Munich, in May 2022.

In a bid to find answers and help determine the “suspicious circumstances” surrounding his death, Interpol have circulated a black notice, which includes facial reconstruction images and physical characteristics of the boy, to its 195 member countries at the request of German authorities.

“Someone, somewhere knows something about this boy, making it equally important to release certain details publicly,” Interpol Secretary General, Jürgen Stock, said in a statement.

“Whether he was the victim of trafficking, abduction or violence, we are committed to mobilising all of Interpol’s policing capabilities to identify him and help investigators shed light on his death.”

The boy, who had brown hair and type 0 blood, was around 110 cm tall and weighed approximately 15kg, according to police.

So far, results of investigations indicate he likely spent time outside of Germany.

It is not known how long the boy’s body spent in the water before it was found on May 19.

Members of the public, “particularly those who remember a missing child whose characteristics and disappearance indicate a potential link” to the boy’s case are urged to contact German police.

Interpol said police can liaise with the organisation for international DNA comparison for “biological relatives who believe the boy could be a member of their family”.

The black notice, which are normally only issued internally among Interpol’s international network of police forces, was issued under the Identify Me program, launched in May.

The program was created as part of a public appeal to identify 22 women who are believed to have been murdered in Belgium, Germany and the Netherlands.