Kevin Connolly BBC Ireland Correspondent

In theory at least, when the IRA decommissioned its weapons last week, its gunmen, bomb-makers and punishment squads found themselves out of work.

Its accountants, cash couriers and portfolio managers however did not.

Laundered cash can generate a legitimate source of income

They are the officials who run an empire of criminality which stretches from the back streets of Belfast through England and on into other countries where the republican struggle against British rule in Northern Ireland means little or nothing.

Now that the British and Irish governments have secured the huge prize of the decommissioning of the IRA's main terrorist arsenal, that empire is likely to find itself under growing scrutiny and growing pressure.

Laundering

The issue of how the republican movement has funded itself and paid for its political ambitions has been headline news since last December when the theft of more than �26m from the Northern Bank headquarters in Belfast was blamed on the IRA.

The organisation had for years robbed banks, operated protection rackets and dealt in smuggled cigarettes and alcohol - as well as raising cash more legitimately from pubs, clubs and taxi businesses which it owned or operated.

The new front line in the struggle against political violence in Northern Ireland will be the accountant's desk and the lawyer's mobile phone Asset raids on properties

The money went in part towards running the republican movement's military campaign.

"Armed struggle" does not come cheap - it's been estimated that the IRA campaign cost as much as �7m a year.

The trick with what is left over of course is to "launder" it - that is to take cash raised from say, selling smuggled cigarettes in west Belfast, and invest it in shares and businesses or property elsewhere.

If that process is carefully managed then the money is "cleaned" so that it cannot be traced back to the original criminal activity.

It then begins to generate legitimate income - if you're a very careful sort of criminal, then you might even consider starting to pay taxes at this point to complete the cleansing of your cash.

'Easy ride'

In 2002, the Proceeds of Crime Act created the Assets Recovery Agency (ARA) which began to unpick the complex paper trails that connect criminals to their investment.

In a sense of course, such arrangements amount to an admission by the authorities that the usual mechanisms of criminal justice - police investigations and prosecutions in court - are almost useless against certain types of paramilitary and gangster.

Those who have had the power to intimidate potential witnesses and jurors have effectively been beyond the law.

Craven Group offices have been raided in Sale, Greater Manchester

Unionists in Northern Ireland have been complaining that the ARA has been used mainly against loyalists and that republicans have been given an easy ride.

Their dark suspicion has been that as long as the British government was attempting to negotiate the decommissioning of IRA weapons, then the IRA's criminal activities would go more or less unchallenged.

They are of course, delighted to see the republican movement under this kind of scrutiny, but they think it should have started much earlier.

Republicans privately see the timing as deeply cynical.

It is 10 days since the IRA decommissioned its weapons and suddenly an operation which has clearly been months if not years in the planning is unleashed against them.

'Securocrats'

If you have ever wondered why Sinn Fein sticks so rigidly to the universally-derided formula that the IRA is a separate organisation - well, on days like this, you see the point.

Beyond the law and the politics though, is an intriguing human aspect to all this

Party representatives can decline to discuss the whole affair on the grounds that it is nothing to do with them.

Although they have a close negotiating relationship with the British government, at moments like this they fall back on another familiar formula.

Anything which reflects badly on the republican movement is the work of "securocrats" - a dark group of police officers and intelligence officials plotting against "the peace process".

It is a formula which hardly sits well with the reality of a Blair Downing Street which has striven endlessly - and occasionally desperately - to get a deal on devolution in Northern Ireland involving Sinn Fein to stick.

Still it allows Sinn Fein to lash out when it is under pressure, and it convinces the faithful.

'Chief of staff'

Beyond the law and the politics though, is an intriguing human aspect to all this.

The man at the end of the paperwork trail which is beginning to unravel in Manchester is Thomas "Slab" Murphy, the shadowy farmer from South Armagh who is widely considered to be the IRA's chief of staff.

He sat for many years on its Army Council alongside Gerry Adams and Martin McGuinness, but is chiefly famous in Ireland for the way he's exploited the location of his family farm - it straddles the Irish border - to make a fortune smuggling fuel and other high value goods.

An underworld rich list once suggested he had made as much as �35m from his dealings although it's not clear how much went to him and how much went to "the cause".

He is not named in the ARA statement, but he is clearly the focus of its operation - if this is the first assault on IRA criminality in many years then it has clearly started at the top.

By their very nature, operations against money laundering are long, and complex.

Someone is going to spend hours - if not years - going through mountains of paperwork armed with a calculator and a suspicious mind - all rather reminiscent of the American authorities' war on the New York mafia.

The new front line in the struggle against political violence in Northern Ireland will be the accountant's desk and the lawyer's mobile phone, not the fields of south Armagh.