The man is described as a light-skinned black man, aged approximately 25, around six foot one inches tall, with "untidy" Afro hair. He was wearing dark clothing and was seen running from the scene into Marylands Road at the time of the incident.
Daniel was shot in the early hours of Saturday 22 May in Harrow Road, near the junction with Sutherland Avenue, Paddington, W9. Officers and London Ambulance Service attended the scene but died at approx. 00:55hrs.
Daniel, who was from the Paddington area and worked as an electrician, lived with his mother and two sisters.
A post-mortem examination held at City of Westminster Mortuary on Saturday 22 May, gave cause of death as a gunshot wound.
Officers from Trident are investigating.