What Stakeknife means to security forces

Denis Murray BBC Ireland correspondent

A few weeks ago Metropolitan Police commissioner Sir John Stevens issued an interim report into collusion between loyalist paramilitaries and the security forces.

The result of 14 years' work by teams of detectives headed by Sir John, it painted an astonishing picture of a British Army intelligence unit and RUC Special Branch members helping and encouraging loyalists to murder Catholics.

Issuing the report, Sir John said his officers intended to interview the IRA agent codenamed Stakeknife, as part of the ongoing collusion investigation.

Sir John Stevens said the agent could be interviewed

One persistent allegation has been that the intelligence services steered loyalists to murder Catholics to protect the safety and identity of the agent, regarded as "the jewel in the crown".

It is also alleged Stakeknife was involved in many murders, including those of other agents, to protect his cover.

Apparently, the security services believe his activities saved many more lives.

The Stevens report established collusion between the security forces and loyalists carrying out murders.

So did the same people that helped loyalists to murder Catholics tolerate or connive in murder by their agent or agents in the IRA?

Turning enemy agents is as old as espionage itself.

This aspect of the Troubles has long been dubbed "the dirty war".

But the question now being asked is - just how dirty did the tactics of the security services become?