The little boy was stabbed last week in Wallsend, Newcastle.
A 29-year-old man was killed.
Peter Duncan was attacked in what police said was an unprovoked “chance encounter”.
No arrests have been made.
A murder investigation has been launched and police are working to track down those involved.
The killing is the 29th fatal stabbing in the capital so far this year.
Gavin Garraway died near Clapham Common tube station.
“He’s not lived his life yet.”