Detectives investigating a fatal stabbing in Westminster have made a fourth arrest.
A murder investigation was launched on 15 July after 18-year-old Ahmed Yassin-Ali, was found with fatal stab injuries in Elmfield Way, W9, at approximately 12.30am.
A 25-year-old was arrested on suspicion of involvement in murder on Thursday, 30 July. He was released on bail to a date in August.
A 23-year-old man and a 17-year-old boy were arrested on suspicion of murder on Friday, 17 July. They have both been released on bail to a date in August.
A 20-year-old man was arrested on 26 July on suspicion of conspiracy to murder. He has been released on bail to a date in August.