Detectives are appealing for witnesses and dash-cam footage after a man died in a collision in Greenford.
Police were called at 8.30pm on Tuesday, 11 August to reports of a collision involving a car and a motorcyclist in Horsenden Lane North.
The motorcyclist, a 25-year-old man, died at the scene. His next of kin have been informed and are being supported by specialist officers.
Four people have been arrested on suspicion of causing death by dangerous driving.
They remain in custody.
Officers from the Met’s Serious Collision Investigation Unit want to hear from anyone who witnessed the collision, or the moments leading up to it.
Anyone with information is asked to call the incident room on 0208 246 9820, quoting CAD 8307/11Aug. Alternatively contact police on 101.