Officers said the individual made the attempt to resuscitate the man between 23:15 and 23:30 hours on Sunday 22 December on Nelson Avenue in St Helier.
A 50-year-old man later passed away in hospital.
It is believed the man who performed CPR was driving a blue Ford Fiesta.
Pictured: The CPR took place on Nelson Avenue in St Helier.
Officers said they would like to speak to the individual in a witness capacity.
CAN YOU HELP?
Anyone with more information is urged to call Police Coroner’s Officer Samantha Rawlinson on 01534 612 942 and quote the reference number ‘M10703′.
