"I have decided not to appeal the sentence imposed by Justice Hulme in relation to the charge of accessory after the fact to murder against Marcus Stanford," the DPP said.
"I have formed the view that there are no reasonable prospects of success on an appeal against the inadequacy of the sentence."
Organisers of the petition however are not giving up, organising a protest march in Leeton which will take place today.
"It's not what we wanted to hear, but that just means we've got to make more noise and keep on keeping on," the petition's creator, Leeton resident Mark Norvall told the ABC of the DDP's decision.
"We're not going to back off on this one, we're not here to get fobbed off or for it not to happen, we want this to be fairly looked at."
"I think you'll find the Leeton community is pretty resilient and they're certainly not slow in coming forward with their views and we will band together and keep fighting for better sentencing."