He was appointed head of Special Branch in December 1989 at the age of 48 . According to the Guardian, "he was the central strategist in the fight against terrorism."
In the months prior to his death, rumours had been circulating in Belfast that he would be leaving the RUC that summer to take up a post as head of security for a Northern Ireland banking institution.
- David McKittrick, New McGuinness would have left old foe amazed, Independent, 24 September 2011.
- Liam Clarke, Dublin's links with IRA shrouded in ambiguity, Belfast Telegraph, 10 February 2012.
- Gerard Cunningham, Ex detective claims one in four IRA members sold information to British, faduda.net, 20 June 2012.
- Tim O'Brien, Ex-garda says he had not known of murders, Irish Times, 21 June 2012.
- Liam Clarke, Key evidence on FRU barred, Sunday Times, 12 September 2004.
- Sally Weale and Owen Boycott, CHINOOK DISASTER: COUNTING THE COST OF THE SENIOR FIGURES IN BATTLE AGAINST TERRORISM, Guardian, 4 June 1994.