A spokesman said: ‘All security personnel are subject to security checking prior to employment and at regular intervals throughout their careers.’The 31-year-old, who is originally from Larne in Co Antrim and was with 40 Commando based at Norton Manor Camp in Taunton, Somerset, at the time of the offences, pleaded guilty to preparation of terrorist acts between January 2011 and August last year, possessing images of bank cards for fraud and possessing cannabis with intent to supply.
His wi-fi password was 'tiocfaidh1', a derivation of the Irish republican phrase 'tiocfaidh ar la', or 'our day will come'.
The Police Service of Northern Ireland have revealed one further arrest has been made but refused to disclose any other details of their further investigations.
A doctor's report said Maxwell had suffered from post-traumatic stress disorder (PTSD) in the immediate aftermath, which persisted into his 20s.
However a prosecutor said there was 'no direct evidence' Maxwell's offending was motivated by the beating.
And that is to cause harm, destruction, and potentially death.'PSNI Detective Chief Inspector Gillian Kearney said Maxwell used his military know-how to accumulate and construct his devices, and described the infiltration of the military by a republican terrorist as 'very unusual' and 'certainly the first case of its kind in recent years'.
The investigation was launched by PSNI after discoveries in March and May 2016, at Carnfunnock Country Park and Capanagh Forest respectively, and police found a large amount of chemicals buried in barrels.
His defence barrister had previously told the court Maxwell 'feared violence' on a daily basis as he grew up as a Catholic in his hometown of Larne.
In 2002, he was 'beaten by golf clubs, iron bars and hammers' and 'left for dead in a field' by loyalists.
Maxwell, who was about to be promoted to Corporal when he was arrested, was at an advanced stage of his 'attack planning'.
He compiled maps, plans and lists of potential targets, as well as images of an adapted PSNI pass card and items of PSNI uniform, addresses of police officers, names of military staff, details of an MI5 member and of loyalists.
Questions have now been raised as to how someone with a background of Republican sympathies passed vetting for the Marines - as police admit it is likely that more of his bombs remain in the hands of senior Continuity IRA members.