Former teacher Sion Jenkins is facing a third trial after a jury failed to decide whether he murdered his foster daughter eight years ago.
Mrs Justice Rafferty discharged the Old Bailey jury after being told on Monday it was unable to reach a verdict.
Mr Jenkins, of Belgravia, London, denied battering 13-year-old Billie-Jo with a tent peg at the family home in Hastings, East Sussex, in 1997.
The 47-year-old will remain on bail as prosecutors seek a third trial.
Nicholas Hilliard, prosecuting, told the judge that the Crown wanted him to face trial again. A hearing will take place in the future to fix a date.