The search for John Beckenridge and 11-year-old Mike Zhao-Beckenridge, of Invercargill, continued yesterday after divers inspected the car on Sunday.
Divers retrieved the engine block number of the dark blue Volkswagen Touareg in Curio Bay, and police confirmed yesterday it was a match for Mr Beckenridge's car, Southland area commander Inspector Kelvin Lloyd said.
The search on Sunday did not reveal any definite information about what was inside the car, he said.
''Police reiterate that the matter is still being treated as a missing persons inquiry and will be continuing to conduct inquiries into locating Mike and John,'' Insp Lloyd said.
A police spokesman said the divers' search gave a ''brief indication there may not be anyone in the car'' but it could not be confirmed until the car was removed from the water.
The engine block was exposed, so divers, working in difficult conditions, could retrieve the number, he said.
Police would continue to work on a way to extract the car from the water.
The school where Michael disappeared from yesterday said any child could leave the school if they really wanted to.
James Hargest College's principal Andrew Wood said the school had no idea how it came to be that Michael was able to leave the school.
''Suffice to say we do not have a brick wall with a barbed-wire fence on the top at our school.
''So any student that is inclined to meet a parent whether they are supposed to or not, it would be quite easy.''
He would not say how much the school knew about the parenting order, only that they had been given some information when Michael was enrolled.
An investigation into how the situation occurred had not been launched.
''It's nothing like a formal review, but we've reflected on our own processes and how the situation unfolded with respect to if there is any possible learning we can take from this.''
He doubted there was anything the school could have done to prevent someone leaving the school.
Auckland University law Prof Warren Brookbanks said schools had an obligation to protect their pupils under the Education Act.
''If they know there is a parenting order in force, they should be at least alerted to that fact and doing what they can within the confines of the school to protect.''
There was a possibility of civil or criminal legal implications, he said.
John Beckenridge, also known as John Robert Lundh, Knut Goran Roland Lundh and John Bradford, was Mike's estranged stepfather, and his contact with the boy was in breach of a parenting order, Insp Lloyd said.
Mike is of solid build and of Asian descent. Mr Beckenridge is 1.75m tall, of medium build and of Swedish descent.
Insp Lloyd said the public should remain vigilant and contact police with any information at the Southern District Command Centre on 03 471-5002 or Crimestoppers on 0800 555 111.
- additional reporting NZME.
