A New Zealand couple who went to Thailand to have a child through IVF and a surrogate have ended up with a baby who has no biological relationship to them.
The heart-breaking mix-up was identified when a DNA test revealed the baby had no genetic connection to either the husband or the egg donor.
A 3D Investigates story about the case will screen on Monday at 9:40pm.
The arrangement involved using the husband's sperm, an egg from a woman who was related to his wife and a Thai surrogate.
But the procedure, carried out in the northern Thai city of Chiang Mai in August 2010, resulted in the couple being told the baby was not theirs.
"Our world just started to collapse," the husband told 3D Investigates. "Straight away I didn't believe it."
Despite the DNA result, which meant the couple were not automatically entitled to bring the child back to New Zealand, the couple were immediately determined to keep him.
"I know that with him not being ours, related biologically, that's obviously an issue…but not for us," said the husband.
But it meant embarking on a protracted and costly legal battle to convince Thai authorities to allow the couple to adopt him.
They persevered, despite being urged to hand over the baby to an orphanage and walk away because it was too difficult.
The boy was eventually allowed to come to New Zealand and now has New Zealand citizenship and a loving home with the couple and their older son – something their lawyer says is only down to their remarkable love for the boy.
"The courage and endurance of these parents have been extraordinary," she told 3D Investigates. "I myself didn't think they would ever get to the point they've got. They've done it through the total selfless love for this child, this child who nobody knew who it was; it was just ghastly.
"I think this child will always be a loved child of this family. They will just have to explain the situation to this child and say, 'We love you. We chose you.' And that's how, what it's all about."
But even having adopted him, the couple has been left with two unanswered questions: who are the baby's biological parents, and what happened to their embryos?
It led to a quest the father compared to Finding Nemo, the Hollywood movie about a fish whose parents have to search for him.
This month, 3D Investigates travelled to Chiang Mai to continue the search – and returned with a breakthrough.
Baby X, 3D Investigates, Monday, TV3, 9:40 pm