Northern Ireland's politicians must deal with the past as well as the future
Anyone who viewed the Panorama programme on the Army spy codenamed Stakeknife, alleged to have headed up the IRA's internal security squad, will have been left in little doubt that the Troubles was indeed a dirty war.
Allegations that the agent was allowed to murder other informers to protect himself are disturbing in the extreme and has led to the establishment of a criminal investigation which will look into the claims.
It will also attempt to ascertain if there is evidence of criminal offences having been committed by members of the British Army, the Security Services or other government personnel, according to the investigation's website.
From material already in the public domain - including the Panorama programme - it is clear that a significant number of individuals, men and women, were killed by the IRA who claimed publicly that they were informers.
In one chilling interview we learned that after being interrogated for a number of days, one man was told he was being taken back to Belfast, but instead was driven to a border location and shot three times in the back of the head as he knelt to say a final prayer.
That was the inglorious reality of how some people met their end. But the concern is that a deeper truth lies behind some of those deaths which will make even grimmer reading if the evidence is uncovered.
We know from other investigations that there was collusion between loyalist killers and state agencies including elements within the RUC, the Army and intelligence services.
And while those bereaved by the Troubles legitimately demand to know the truth about why their loved ones died and want justice for their loss, there will be many on all sides of the conflict who won't want that particular Pandora's Box opened.
Who will willingly confess to their part in squalid killings such as the one outlined above or incidents of mass murder and maiming which left even those who carried them out ashamed of their deeds.
Viewed through this prism, it can be easily understood how dealing with the past is such a sticking point among the political parties. Secretary of State James Brokenshire says some further progress has been made on legacy issues, but further distance has yet to be travelled.
There are other significant differences which have yet to be resolved and he has moved the deadline further back to allow the parties breathing space to attempt to reach an accommodation which would lead to the restoration of a devolved administration.
But, while Mr Brokenshire must still say that he holds out hope of a deal, his language and the general atmosphere of pessimism among the public and even some politicians does not augur well.
Yet all these issues are not going to go away and the demands of the bereaved will still echo in the politicians' consciousness. Failing to do something substantial to address those demands before now is shameful, but it will be unforgivable if the victims continue to be denied.
If the parties, seemingly against the odds, can reach agreement it is imperative that it is one which will stand the test of time. We cannot allow the administration to fall apart every time a major issue has to be confronted. No one says that the politicians' task is an easy one but, as Mr Brokenshire said, they have been mandated by the election to form a government. They cannot ignore the electorate.