Justice John Roderick McKechnie yesterday acquitted Schmidt of murder but found him guilty of manslaughter.
Last night he was sentenced to nine years' imprisonment.
The couple had braced themselves for the gruelling nature of the retrial, which was expected to have a heightened focus on the injuries leading to their son's death.
Mr Marshall told Hawke's Bay Today the couple were accepting of Schmidt's sentence yesterday but there were elements of the retrial they had not agreed with.
"We definitely respect the decision the judge has made," he said. "We don't agree with all the findings. We don't agree with everything, but we'll just have to accept it."
He said it would have been a mistake for them to go to the retrial looking for satisfaction or closure.
"It's never going to be enough to bring closure for us. I don't think we'll ever get closure."
The delivering of the couple's victim impact statements before yesterday's sentencing had been "very emotional".
"We feel battered and bruised. It takes a greater toll than you realise." The Marshalls planned to take time out with Mr Marshall's brother in Brisbane before coming home. At the opening of the retrial 11 days ago, Schmidt offered to plead guilty to the lesser charge but prosecutors rejected the plea deal.
Andy Marshall was a cousin of slain Feilding farmer Scott Guy, who was shot in his driveway in 2010.