The three others in the car, including McKenna's older brother Damien, were rearrested in Northern Ireland. All three pleaded guilty and received 15-year prison sentences in 2009.
Another McKenna brother, Daire, received a nine-year prison sentence in 2008 after police linked him and two other Continuity IRA members in Lurgan to two sheds containing 110 kilograms (240 pounds) of fertilizer-based explosive, a key component of IRA car bombs.
Lurgan, southwest of Belfast, is the primary power base of the Continuity IRA, a small anti-British paramilitary group that broke away in 1986 from the dominant faction, the Provisional IRA. The Continuity IRA and other splinter groups have continued to plot gun and bomb attacks in Northern Ireland in defiance of the Provisional IRA's 2005 decision to renounce violence and disarm.
The Provisional IRA killed nearly 1,800 people during a failed 1970-1997 campaign to force Northern Ireland out of the United Kingdom. In 2007, weeks before the thwarted Lurgan mortar attack, former Provisionals from the Irish nationalist Sinn Fein party formed a power-sharing government with leaders of Northern Ireland's British Protestant majority.
The IRA splinter groups today still hope to undermine public support for that unity government, Catholic support for the police, and other achievements of Northern Ireland's two-decade peace process. They have killed two British soldiers, two policemen and a prison guard since 2007, but the bulk of their attacks fail either through faulty bombmaking or anti-terrorist surveillance.
The Republic of Ireland long provided a safe haven for IRA members fleeing arrest and criminal charges in Northern Ireland, as Irish judges in the 1970s and 1980s consistently ruled that IRA members were politically motivated and exempt from extradition. That policy changed following treaties that boosted British-Irish cooperation on combating the rival IRA factions, which typically fund their operations with bank robberies, protection rackets, border smuggling and counterfeiting.