Police have been unable to contact the couple, described as being of Pacific Island descent.
"This couple are said to have witnessed the incident, so it is important that we speak with them.
"Police would also like to thank them for stopping to help."
Following the incident, the man was taken to Auckland City Hospital in a critical condition.
He suffered a serious head injury and required a lengthy stay in hospital and continues to recover from the injuries he sustained that night.
"The nature of his injury means that this will be a lengthy, ongoing process."
Police have conducted a number of enquiries into the incident including examining CCTV footage in the wider area.
"Police are keeping an open mind as to whether the male has been struck by a vehicle or has simply fallen from his skateboard.
"The impacts of the male's injuries means he has little recollection of the night, so it is vital that anyone who has information comes forward."
If anyone was in the area at the time and witnessed the incident, or knows the couple who stopped, they can contact Henderson Police on 105 and quote the file number 200201/6108.