Does this mean that the IRA didn't really completely decommission their arms?

Police Officer Ronan Kerr was killed by men who until recently were members of the Provisional IRA. Police Officer Ronan Kerr was killed by men using IRA weapons, weapons that should have been decommissioned. So two questions come to mind: first how did Ronan Kerr's killers get access to Provo weapons and second does this mean that the IRA did not really decommission all of their arms?

The second question is one that I suspect we all know the answer to... Can we expect a statement from Gerry Adams and Martin McGuinness and if so should we believe a word that they say?