A 14-year-old boy has been charged with the murder of James Markham, who was stabbed in Chingford, northeast London, on Monday evening.
The Metropolitan Police said the boy has also been charged with possession of a knife in a public place and breach of a Criminal Behaviour Order (CBO).
He will appear at Stratford Youth Court on Friday.
A second boy, also 14, who was arrested on suspicion of conspiracy to murder, and a 16-year-old who was arrested on suspicion of assisting an offender have been released under investigation, the force said.
Police were called to Churchill Terrace in north east London at 6.20pm.
Mr Markham, 45, was attacked after reportedly trying to defend his daughter.
Members of the public tried desperately to save Mr Markham along with officers and paramedics but he died at the scene.
A post-mortem examination confirmed he died of a stab wound to the lung.
Anyone who witnessed the incident, or has information about what took place, is urged to call police on 101 or tweet @MetCC, giving the reference 5735/09AUG.
