London, Mar 8 : Murdered Harry Potter star Rob Knox's father has branded his son's killer `spineless scumbag.'

Karl Bishop was given life sentence after he was convicted of the attack on Rob, reports the News of the World.

Rob had been stabbed five times in the chest by Bishop, 22, outside the Metro bar in Sidcup, south east London, in May last year.

Bishop never once showed a sign of remorse, repeatedly laughing and giving thumbs-up signs to pals at the Old Bailey in London.