Magee joins the Belfast Brigade of the IRA and receives a five-year sentence in 1971 for possession of firearms. He is imprisoned in Long Kesh, where he holds the position of camp adjutant. In the late 1970s and early 1980s he is part of a four-man active service unit, along with Joe Doherty and Angelo Fusco, nicknamed the “M60 gang” due to their use of an M60 general-purpose machine gun. On April 9, 1980, the unit lures the Royal Ulster Constabulary (RUC) into an ambush on Stewartstown Road, killing Constable Stephen Magill and wounding two others. On May 2 the unit is planning another attack and has taken over a house on Antrim Road, when an eight-man patrol from the British Army‘s Special Air Service (SAS) arrives in plain clothes, after being alerted by the RUC. A car carrying three SAS members goes to the rear of the house, and another car carrying five SAS members arrives at the front of the house. As the SAS members at the front of the house exit the car the IRA unit opens fire with the M60 machine gun from an upstairs window, hitting Captain Herbert Westmacott in the head and shoulder. Westmacott is killed instantly and is the highest-ranking member of the SAS killed in Northern Ireland. The remaining SAS members at the front of the house, armed with Colt Commando automatic rifles, submachine guns and Browning pistols, return fire but are forced to withdraw. Magee is apprehended by the SAS members at the rear of the house while attempting to prepare the IRA unit’s escape in a transit van, while the other three IRA members remain inside the house. More members of the security forces are deployed to the scene, and after a brief siege the remaining members of the IRA unit surrender.
The trial of Magee and the other members of the M60 gang begins in early May 1981, with them facing charges including three counts of murder. On June 10 Magee and seven other prisoners, including Joe Doherty, Angelo Fusco and the other member of the IRA unit, take a prison officer hostage at gunpoint in Crumlin Road Jail. After locking the officer in a cell, the eight take other officers and visiting solicitors hostage, also locking them in cells after taking their clothing. Two of the eight wear officer’s uniforms while a third wears clothing taken from a solicitor, and the group moves toward the first of three gates separating them from the outside world. They take the officer on duty at the gate hostage at gunpoint and force him to open the inner gate. An officer at the second gate recognises one of the prisoners and runs into an office and presses an alarm button, and the prisoners run through the second gate towards the outer gate. An officer at the outer gate tries to prevent the escape but is attacked by the prisoners, who escape onto Crumlin Road. As the prisoners are moving toward the car park where two cars are waiting, an unmarked RUC car pulls up across the street outside Crumlin Road Courthouse. The RUC officers open fire, and the prisoners return fire before escaping in the waiting cars. Two days after the escape, Magee is convicted in absentia and sentenced to life imprisonment with a minimum recommended term of thirty years.
Magee escapes across the border into the Republic of Ireland. Eleven days after the escape he appears in public at the Wolfe Tone commemoration in Bodenstown Graveyard, County Kildare, where troops from the Irish Army and the Garda‘s Special Branch attempt to arrest him but fail after the crowd throws missiles and lay down in the road blocking access. He is arrested in January 1982 along with Angelo Fusco and sentenced to ten years imprisonment for the escape under extra-jurisdictional legislation. Shortly before his release from prison in 1989, he is served with an extradition warrant, and he starts a legal battle to avoid being returned to Northern Ireland. In October 1991, the Supreme Court of Ireland in Dublin orders his return to Northern Ireland to serve his sentence for the murder of Captain Westmacott, but Magee jumps bail and a warrant is issued for his arrest.
Magee flees to England, where he is part of an IRA active service unit. On June 7, 1992, Magee and another IRA member, Michael O’Brien, are traveling in a car on the A64 road between York and Tadcaster, when they are stopped by the police. Magee and O’Brien are questioned by the unarmed police officers, who become suspicious and call for back-up. Magee shoots Special Constable Glenn Goodman, who dies later in hospital, and then shoots the other officer, PC Kelly, four times. Kelly escapes death when a fifth bullet ricochets off the radio he is holding to his ear, and the IRA members drive away. Another police car begins to follow the pair, and comes under fire near Burton Salmon. The lives of the officers in the car are in danger, but Magee and O’Brien flee the scene after a member of the public arrives. A manhunt is launched, and hundreds of police officers, many of them armed, search woods and farmland. Magee and O’Brien evade capture for four days by hiding in a culvert, before they are both arrested in separate police operations in the town of Pontefract.
On March 31, 1993, Magee is found guilty of the murder of Special Constable Goodman and the attempted murder of three other police officers and sentenced to life imprisonment. O’Brien is found guilty of attempted murder and receives an eighteen-year sentence. On September 9, 1994, Magee and five other prisoners, including Danny McNamee, escape from HM Prison Whitemoor. The prisoners, in possession of two guns that had been smuggled into the prison, scale the prison walls using knotted sheets. A guard is shot and wounded during the escape, and the prisoners are captured after being chased across fields by guards and the police. In 1996 Magee stages a dirty protest in HM Prison Belmarsh, in protest at glass screens separating prisoners from their relatives during visits. He has refused to accept visits from his wife and five children for two years, prompting Sinn Féin to accuse the British government of maintaining “a worsening regime that is damaging physically and psychologically.”
In January 1997, Magee and the other five escapees from Whitemoor are on trial on charges relating to the escape for a second time, as four months earlier the first trial had been stopped because of prejudicial publicity. Lawyers for the defendants successfully argued that an article in the Evening Standard prejudiced the trial as it contained photographs of Magee and two other defendants and described them as “terrorists,” as an order had been made at the start of the trial preventing any reference to the background and previous convictions of the defendants. Despite the judge saying the evidence against the defendants was “very strong”, he dismisses the case stating, “What I have done is the only thing I can do in the circumstances. The law for these defendants is the same law for everyone else. They are entitled to that, whatever they have done.”
On May 5, 1998, Magee is repatriated to the Republic of Ireland to serve the remainder of his sentence in Portlaoise Prison, along with Liam Quinn and the members of the Balcombe Street Gang. He is released from prison in late 1999 under the terms of the Good Friday Agreement and returns to live with his family in Tralee, County Kerry. On March 8, 2000, he is arrested on the outstanding Supreme Court extradition warrant from 1991 and remanded to Mountjoy Prison. The following day he is granted bail at the High Court in Dublin, after launching a legal challenge to his extradition. In November 2000 the Irish government informs the High Court that it is no longer seeking to return him to Northern Ireland. This follows a statement from Secretary of State for Northern Ireland Peter Mandelson saying that “it is clearly anomalous to pursue the extradition of people who appear to qualify for early release under the Good Friday Agreement scheme, and who would, on making a successful application to the Sentence Review Commissioners, have little if any of their original prison sentence to serve.” In December 2000 Magee and three other IRA members, including two other members of the M60 gang, are granted a Royal Prerogative of Mercy which allows them to return to Northern Ireland without fear of prosecution.