The family of a police officer killed by the IRA has asked the Police Ombudsman to investigate claims Special Branch failed to prevent the attack.
The 34-year-old constable died in an IRA attack on her police vehicle
Police informer Kevin Fulton claims Constable Colleen McMurray was murdered in Newry, despite the fact Special Branch had been warned of the attack by a British agent.
A spokesman for Police Ombudsman Nuala O'Loan confirmed the case was being investigated.
The 34-year-old constable was killed in an IRA attack on her police vehicle in Newry in 1992.
A male colleague lost his legs in the attack.
There have been allegations that the attack could have been prevented because one of the bomb makers was working for the intelligence services.
DUP MP Jeffrey Donaldson has said the family just wanted to know the truth.
"They are going to look at the circumstances and events that occurred leading up to the murder of Colleen McMurray," he said.
"They are going to look at what intelligence was made available to the security services prior to the murder and how that intelligence was handled during the police investigation."
Meanwhile, an inquiry into the functions of the Ombudsman's office is to be conducted by the parliamentary Northern Ireland Affairs Committee.
The committee said it wished to look at progress towards developing a role for the Police Ombudsman since the office was established in November 2000.
It said it also wanted to study the performance of the office in respect of its principal activities and the "efficiency and effectiveness of the administration and expenditure of the office", including its performance against key indicators and targets.
The committee, chaired by Conservative MP Michael Mates, has invited any individual or organisation with an interest to submit written evidence to them
by late March.