This week saw the opening of the public inquiry into the death of Robert Hamill, the Catholic man beaten and kicked to death in a sectarian attack in Portadown in 1997. Such attacks happen frequently, even in peaceful Northern Ireland. So why has this one attracted a lengthy and expensive |inquiry?

Quite simply because the family don't believe all the evidence of what happened on that night has yet been made public. There were |allegations that uniformed policemen in a Land Rover saw the attack but did nothing. A further allegation is that one of the reserve constables in the vehicle warned one of the attackers to dispose of his clothing and kept him updated about the police investigation.

It is one of a number of inquiries which are on-going, due to start or are just completed. Those include the |inquiries into Bloody Sunday, when 13 people were shot dead by paratroopers in Londonderry: Pat Finucane, the Catholic lawyer shot dead by loyalists who included security forces agents; Rosemary Nelson, the lawyer killed by a bomb attached to her car; Billy Wright, the LVF leader shot dead in the Maze Prison; and, Chief Superintendent Harry Breen and Superintendent Bob Buchanan, two police officers shot dead in an IRA ambush in south Armagh, |allegedly after a tip-off from a rogue Garda |officer.

All these incidents have one thing in common. The relatives of the deceased don't believe the truth about the deaths has yet been revealed; indeed, in some instances they feel there has been a cover-up.

The inquiry that has attracted the most criticism to date is the one into the events of Bloody Sunday.

Critics have tried to undermine it by highlighting its huge cost — estimates vary from £181m to £400m. In any case it was very, very expensive. Indeed it was cited as the reason why there would not be a public inquiry into the Tube and bus bombings in London in 2007.

But what the critics don't mention is that the Bloody Sunday inquiry was only necessary because the Government tried to cover its tracks — or at least the Army's — through the original Widgery Inquiry. Lord Widgery maintained the Army had been fired on first but Prime Minister John Major, years later, said all those killed should be regarded as innocent of any allegation that they were shot while handling firearms or explosives.

Widgery was regarded as a whitewash. Had the Government admitted at an early stage that the Army's actions on the day were indefensible, thereby exonerating the people shot, then there would have been no need for the Saville inquiry whose verdict is due in 2010.

In the Finucane and Nelson inquiries the |attention is on collusion between loyalist paramilitaries and either the police or army. Again the families feel this relationship between agents and their state handlers needs to be ventilated.

A similar feeling exists in the case involving the deaths of the two high-ranking RUC officers, Harry Breen and Bob Buchanan. Were some gardai in cahoots with the IRA?

David Wright, the father of LVF man, Billy Wright, is asking the same sort of questions as regards his son's death. Did authorities in the Maze Prison, or others, know of a republican plot to kill him before they actually succeeded in doing so? There will be more complaints that these inquiries are unnecessary and that they are too expensive.

They are not unnecessary. Uncovering the truth, no matter how unpalatable, is worth |almost any cost and as much work as it takes.

Bloody Sunday, for example, was a seminal event in the escalation of the Troubles and the growth of the IRA’s killing machine. Thirteen people were shot dead by the Army on the streets of a UK city and a 14th later died of injuries caused on the day.

We know those people were innocent of any crime. The Prime Minister said so. So why were they killed? That is an important question that must be answered.

And it is the same question that is being asked in the other inquiries and the same answers that are being demanded.

The relatives have every right to know why their loved ones died. The state, in the view of many, could provide the answers without any inquiries if it so felt like it. But it doesn't, so we need inquiries.