Wikipedia
Stakeknife is the code name of a spy who infiltrated the Provisional Irish Republican Army (IRA) at a high level, while working for the top secret Force Research Unit (FRU) of the British Army. Reports claim that Stakeknife worked for British intelligence for 25 years.
Stakeknife had his own dedicated handlers and agents and it was suggested that he was important enough that MI5 set up an office dedicated solely to him. Rumours suggested that he was being paid at least £80,000 a year and had a bank account in Gibraltar.
Serious allegations have emerged to the effect that the British government allowed up to forty people to be killed via the IRA's Internal Security Unit or "Nutting Squad" to protect his cover. In 1987 Sam McCrory, an Ulster Defence Association/"Ulster Freedom Fighters" member, killed the 66-year-old Francisco Notarantonio at his home in Ballymurphy in West Belfast. The UDA/UFF had discovered that a senior IRA member was working for the FRU. It has been alleged that FRU agent Brian Nelson gave Notarantonio's name to the UDA/UFF to protect the identity of the real spy.
On 11 May 2003, several newspapers named Freddie Scappaticci as Stakeknife. Scappaticci denied the claims and launched an unsuccessful legal action to have the British government state he was not their agent. He later left Northern Ireland and was rumoured to be living in Cassino, Italy. There were also reported sightings in Tenerife.
A report in a February 2007 edition of the Belfast News Letter reported that a cassette recording allegedly of Scappaticci talking about the number of murders he was involved in via the "Nutting Squad", as well as his work as an Army agent, had been lodged with the PSNI in 2004 and subsequently passed to the Stevens Inquiry in 2005.
The former British Intelligence agent who worked in the FRU known as " Martin Ingram" has written a book titled Stakeknife since the original allegations came to light in which it says Scappaticci was the agent in question.
In October 2015 it was announced that Scappaticci was to be investigated by the Police Service of Northern Ireland over at least 24 murders. In June 2016 it was announced that this investigation would be carried out by Bedfordshire Police and would examine the possible involvement of members of the RUC, Army and MI5 in murders carried out by the IRA, and their knowledge of them through the information supplied via Stakeknife.