A jury has found Taranaki farmer David Roigard guilty of the murder of his son Aaron Roigard.
The verdict was reached after about seven hours of deliberations in the High Court at New Plymouth, where David Roigard, 51, has been on trial for five weeks.
He has also been found guilty of eight charges of theft in a special relationship.
The Crown said Roigard killed Aaron Roigard, 27, in June last year when he could no longer conceal he had stolen more than $66,000 from him.
Mr Roigard was last seen at his father's Waiteika Road home in Opunake on 2 June 2014.
His bank account and cellphone have not been used since, and extensive land, sea and air searches have failed to locate a body.
The officer in charge of the case, detective senior sergeant Blair Burnett, said he had unfinished business - finding Mr Roigard's body.
He said he had promised to return Mr Roigard home and he would not give up.
He said police would continue to make inquiries and, at some stage, they would approach Roigard to see if he was willing to assist them further.
Mr Burnett said without a body it had been a difficult case, and his team could not have wished for more from the verdict.
Roigard will be sentenced on 15 February 2016