Controversial former Ministry of Defence information officer Mr Colin Wallace, who has made numerous allegations of official dirty tricks in Northern Ireland, is expected to give evidence to the Bloody Sunday Inquiry this morning.
Mr Wallace was based at army headquarters in Northern Ireland in 1972 when 13 civilian civil rights marchers were shot dead by paratroopers in Derry.
Through the violence of the early 1970s Ulster born ex-soldier Mr Wallace briefed the visiting media - allegedly spreading black propaganda on behalf of his MoD masters.
He was sacked in 1975, ostensibly for leaking a classified document to a Belfast-based reporter. He claimed it was for threatening to expose a homosexual ring at the Kincora boys' home in east Belfast which was run by extreme loyalist Mr William McGrath, now dead.
Five years later the Kincora affair was finally exposed in an Irish newspaper and three men convicted of sexual abuse. Within months Mr Wallace was charged with the murder of his best friend, Mr Jonathan Lewis, who was found floating in the River Arun at Arundel, West Sussex.
He protested his innocence but was found guilty of manslaughter in 1981 and jailed for 10 years. He served six years of the sentence before being released on parole.
While in prison he sent a dossier to the then British prime minister Mrs Margaret Thatcher alleging a dirty tricks campaign in Northern Ireland in the early 1970s.
But after his allegations were repeatedly raised by MPs - notably Mr Ken Livingstone - it was finally admitted in 1990 that such a dirty tricks campaign had been in operation.
After an investigation into his sacking, Wallace was awarded £30,000 sterling compensation for wrongful dismissal. Finally in 1996, the Court of Appeal overturned his manslaughter conviction.
PA