Finding Scott Guy's killer will always hinge on someone coming forward with information, says his father.
Mr Guy was gunned down on his Fielding property on July 8, 2010. Nobody has been brought to justice for the killing, although police say the file remains open.
His brother-in-law Ewen Macdonald was acquitted of Mr Guy's murder at a trial in 2012, although he is serving five years in jail for other crimes.
Now his widow, Kylee, has had to end her privately funded investigation into her husband's death due to a lack of funds.
The slain farmer's father, Bryan Guy, said the family hoped that one day they would find out the truth about the murder - but any investigation hinged on someone coming forward with vital information.
"Obviously somebody knows something, so until that information comes to light there is not a lot that can be done."
However, Mr Guy said the family was focused on moving forward.
"We always hope that something is going to come out of further investigations, but if you just dwell on that it's going to eat us up, we have got to get on with life."
He said the family was in regular contact with Mrs Guy, but were not involved in her investigation.
They supported her efforts, but also had confidence in the police investigation.
"They always said they would keep us informed if anything comes to light, but we haven't spoken to them in some time."
A Parole Board spokesman said MacDonald will appear before the board next month.
His current sentence is due to end of April 6, but he has completed farm work while on day release from Rolleston Prison in Canterbury.
In 2012, he pleaded guilty to offences committed between December 2006 and January 2009 - including burning down Kylee and Scott Guy's old farmhouse; a vandalism attack on the new home they were building; killing 19 calves with a hammer; poaching deer; destroying a milk supply and burning down a neighbour's duck hunting whare.
The hearing will discuss MacDonald's rehabilitation in prison and could result in bail.
It will be closed to media, but the outcome will be released afterwards.