Two 17-year-olds have been charged with the murder of a man with learning difficulties, police said.
The male youths also face charges of conspiracy to rob and possession of an offensive weapon, Scotland Yard said.
Dean Mayley, 24, was stabbed in the heart as he walked along Ruislip Road, Greenford, west London, on February 7.
He suffered from a development disorder which led to him having moderate learning difficulties and the mental age of a nine-year-old.
A post-mortem examination gave the cause of death as a single stab wound to the chest.
The two teenagers are due to appear in custody at Willesden Youth Court today.