An escape remains a possibility - in one of New Zealand's most baffling missing person's cases

John Beckenridge disappeared from the Catlins with stepson Mike Zhao-Beckenridge in 2015 - after taking the boy from his Invercargill school, breaking a court order.

A coroner is working to decide if the pair died when their car fell off an 88-metre cliff - or if it was staged.

No bodies have ever been found.

Questions have been raised about whether a stake on the clifftop marked where to jump from the vehicle, before it fell into the water waters below.

A private investigator has also questioned whether the pair evaded Police and left the Catlins, before the car was found.