Born: September 29, 1946; Died: June 16, 2012.

Sir Alasdair Fraser, who has died aged 65 of cancer, was a Scots-born former Director of Public Prosecutions in Northern Ireland. He filled the post for 21 years and was a pillar of the legal establishment during the Troubles, living under security constraints, always aware he was an assassination target.

He was born in Glasgow but moved with his family to Northern Ireland in 1950. He took a law degree at Trinity College Dublin and returned to study at Queen's University Belfast. He was called to the Northern Ireland Bar in 1970, then practised for three years before joining the Department of the Director of Public Prosecutions. A year later he was Assistant Director of Public Prosecutions.

He became deputy in 1988 and in 1989 Attorney-General Sir Patrick Mayhew, appointed him as DPP for Northern Ireland. He served under six Attorney-Generals and oversaw the office's transition into a body that assumed responsibility for all prosecutions – most were previously in the hands of the police.

He was DPP as Northern Ireland made the transition from conflict to peace, at a time when ceasefires were called and the Belfast Agreement was cemented.

It was also his responsibility to deal with some of the most serious cases in those turbulent times: the murder of Republican lawyer Pat Finucane; the first and subsequent Stevens inquiries into alleged collusion between loyalist paramilitaries and the state security; John Stalker's report into allegations of a shoot-to-kill policy, and the use of informants' evidence.

He was chairman of the Church of Ireland's Young Men's Society rugby club in Belfast and overcame loyalties when Ireland played Scotland in the Six Nations by supporting whichever team won.

Knighted in 2000 for services to the criminal justice system, he is survived by his wife Margaret, a daughter and two sons.