An eagerly awaited testimony

Fourteen civilians died after being shot on Bloody Sunday

By the BBC's Ireland correspondent Tom Coulter

When Martin McGuinness takes the witness stand at the Bloody Sunday Inquiry, his will be the most eagerly awaited testimony of any witness to the tribunal.

It is expected that he will admit to being second-in-command of the Provisional IRA's Londonderry brigade on that fateful day in January 1972.

That was the day soldiers from the British Army's Parachute Regiment opened fire on a civil rights march and shot dead 13 unarmed civilians.

A 14th man died later.

Martin McGuinness: To take witness stand

The education minister's decision to give evidence to the tribunal, set up to establish the truth of what happened almost 30 years ago, is significant in a number of ways.

In admitting that he was a senior member of the IRA, and disclosing some of its plans for the day that became known as Bloody Sunday Mr McGuinness will be breaking one of the organisations key rules - the oath of secrecy.

It is likely he has been given permission to break the vow of silence by the IRA's ruling army council.

If Mr McGuinness is to face questioning about the IRA and his role in it on Bloody Sunday, then others will want to know his role in it before and after Bloody Sunday.

Killings

If he is giving evidence to the Saville Inquiry to help the families of those killed get to the truth and come to terms with what happened on that awful day, then surely other bereaved families will want him to help them.

The families of two police officers shot dead by the IRA in Derry just a few days before Bloody Sunday, could argue that, they too, are entitled to the same consideration.

They could ask him to say why their loved ones were targeted and shot and if he knew about, or ordered, the killings.

There could also be some awkward questions about the relationship between Sinn Fein and the IRA.

In recent years, Sinn Fein has denied there is any link and repeatedly said it cannot speak for the paramilitary group.

British soldiers in Derry on Bloody Sunday

Now, one of the most senior members of Sinn Fein is admitting he was also a senior member of the Provisional IRA.

Mr McGuinness's political opponents will also want to know if the man in charge of the education of Northern Ireland's children is still a member of the IRA, and if not, when did he leave.

There is no doubt Mr McGuinness was under pressure to give evidence to the Bloody Sunday Inquiry.

Sinn Fein and the families of those killed have long campaigned for a fresh inquiry, insisting they wanted to get to the truth of what happened on that day.

It would have been seen as hypocritical of Mr McGuinness to expect Parachute Regiment soldiers to bare their souls, while he refused to give evidence or deny any knowledge of the IRA or its plans.

And Sir Reg Empey had put it, "the dogs in the street know he was a senior member of the IRA."

There is also a school of thought that the decision to allow such a high profile member of Sinn Fein to admit his IRA links is an indication the republican movement believes the armed struggle is over - and politics is the only way forward.