Two more teenagers have been arrested on suspicion of the murder of a vulnerable man in west London.
The men, aged 17 and 18, handed themselves into a north London police station where they were arrested. They remain in custody.
Two other 17-year-olds have been accused of murder, and appeared in court on Monday.
The arrests follow police appeals after Dean Mayley, who had learning difficulties, was allegedly stabbed to death by a gang of three or four men as he walked along a street in Greenford on Friday, February 7.
His family said Dean, who was 24 but had a mental age of nine, was very vulnerable and easily led.
The investigation into his death is ongoing.
Anyone with information is asked to call police on 0208 358 0200 or contact Crimestoppers anonymously on 0800 555 111.
