A man remains critically ill in hospital after being attacked in the centre of Oxford five days ago.
The 21-year-old needed emergency brain surgery after the assault on Gloucester Street on Friday.
He is in the intensive care unit at the John Radcliffe Hospital.
Detectives believe people in the garden of the Goose Pub may have witnessed the attack, and have appealed for them to get in contact.
The assault happened at about 2030 BST Friday.