There are about 400 people listed as missing in New Zealand.
For the past five months, Three's The Project has been investigating one of the most mysterious cases - that of Auckland man Jim Donnelly.
Mr Donnelly left for work 13 years ago and was never seen again.
He arrived at work and later in the morning was seen by his colleagues pacing around, which is the last known sighting.
An hour later, Mr Donnelly's wife rang his mobile phone, but couldn't get through.
His colleagues then started looking for the father - and found his car was still at work. Later in the day, he was reported missing to police.
Five days after he was reported missing, his hard hat was found next to an acid tank. His belongings were found inside, but police concluded the acid was not strong enough to dissolve a body.
More than a decade later, the family has been left with four possibilities - accidental death, suicide, a staged disappearance or murder.
The Project returns to the day he vanished in the first part of a special series, entitled 'Missing Jim'.
Watch the video for The Project's full report.
