Halifax police are looking for a witness in the murder of a 16-year-old boy at the Halifax Shopping Centre.

Police say a driver of a motorcycle saw the incident and helped the victim.

The driver was wearing grey pants, a dark-coloured jacket with stripes on the sleeves and a black helmet.

Ahmad Al Marrach was stabbed in the parking lot of the mall, April 22.

He was taken to hospital where he later died from stab wounds.

Four teenagers charged with second degree murder in the case, remain in custody, and will be tried together.

Investigators have taken all steps but have not been able to identify the driver.

Police are asking the individual or anyone with information on their identity to call police at 902-490-5020.