Police believe occupants of a 2004 Mitsubishi Grandis hold crucial information in regards to the death of a man who was assaulted at an Auckland bus stop

33-year-old U.S PhD student, Kyle Whorrall died following head injuries after an attack in St John's over Easter weekend.

A 16-year-old boy's been charged with murder - and a 32-year-old woman has been charged with being an accessory after the fact to murder.

Police are appealing for those connected to the silver Mitsubishi Grandis - registration GNG652 to come forward.

They say the vehicle may have travelled to Northland in recent days.