Allegations that MI5 agents may have been involved in the murder of Real IRA man Kieran Doherty are to be investigated by the government's independent advisor on the activities of the security services.
Lord Alex Carlisle will also investigate claims that information is being withheld from detectives.
The 31-year-old was found shot dead on the outskirts of Londonderry this year.
The Real IRA said he had been killed because of links to the drugs trade.
His family rejected the claim and said they believed members of the security services may have been involved in his murder
Lord Carlisle, the government's independent advisor on how MI5 operates here, has agreed to meet the family and to investigate their claims.
Kieran Doherty was a senior member of the Real IRA and a lifelong republican.
In the months before he was killed, he told a local newspaper that MI5 had tried to recruit him as an agent.
Kieran Doherty's uncle, Vincent Coyle, said the family had a number of questions about the role of MI5 in the case.
"What's most important is where were they on the night of Kieran's abduction, stripping and murdering," he said.
"Some of the family members have voiced the opinion that they believe members of MI5, who have somehow got into this organisation, may have been at the scene, may have been involved in the abduction and may have been involved in the murder."
The offer to meet Kieran Doherty's family was made in a letter to Foyle MP Mark Durkan, who has lobbied on their behalf. He welcomed the move, but urged caution about the outcome of the investigation.
Lord Carlisle is due to travel to Derry to speak to Kieran Doherty's family.
Speaking to Home Affairs correspondent Vincent Kearney, he said he will listen to their allegations and consider any evidence they produce.
He will then speak to the security services and report on his findings to the Secretary of State.