Shauna Moreland, whose 34-year-old mother Caroline was abducted and murdered by the IRA as an alleged informer in 1994, said she was delighted at the announcement of the Stakeknife investigation.
"It has been a long road struggling to get recognition that our loved ones are as deserving of justice as anyone else who was killed during the conflict, because for years their lives were swept aside," she explained
Ms Moreland also said was "very satisfied" with John Boutcher's pledge to "leave no stone unturned" in finding the truth. "I just hope he now lives up to his words," she added.
"He has said that the investigation will take five years. That seems a bit long to me but, given that my mum is dead 22 years, I suppose another five isn't huge in the grand scheme of things."
Ms Moreland praised the PSNI Chief Constable for agreeing to an independent investigation. "By allowing someone from outside his force to lead the investigation, George Hamilton did the right thing," she said. "He has also done his best to source funding for the investigation and, I believe, ensure that it is fair."
Frank Mulhern, whose 23-year-old son Joseph was shot dead by the IRA as an alleged informer in 1993, also welcomed news of the new investigation into Stakeknife.
"The PSNI and the RUC had years and years to do something about this and there was no movement, so I'm glad it's with somebody else now," he said.
"But I don't see why the investigation should take as long as five years. All of the information that is needed is already there."
Mr Mulhern also indicated he was hopeful that the Police Ombudsman, Dr Michael Maguire, would make significant progress during his investigation into the murders allegedly carried out by Stakeknife.
"The ombudsman didn't spare the whip with his investigation into Loughinisland, so I've a lot of faith in him," Mr Mulhern said.