Former loyalist terrorist David Ervine was an example of the power of redemption, former US Senator George Mitchell said tonight.
The Loyalist Ulster Volunteer Force (UVF) member was an inspiration in turning his focus to politics and helping Northern Ireland emerge from 30 years of violence, Mr Mitchell added.
Mr Ervine died last year and Mr Mitchell paid tribute to his memory at a conference in Belfast.
"He represented evidence or proof of the power of redemption. He was a great man but not a saint," he said.
"He made mistakes and became involved in violence early on.
"We are all human and all make mistakes but we all don't learn from them. David Ervine did, and he came out of prison determined to do something to promote peace and reconciliation, and he did."
Mr Ervine was sentenced to 11 years in prison after he was found guilty of possession of explosives.
After his release in 1980 he joined the Progressive Unionist Party (PUP) in his native east Belfast and in 1998 became an Assembly member as its leader. He had been on Belfast City Council since 1997.
Mr Mitchell established the principles of non-violence during the Northern Ireland peace process as US special envoy to the country from 1995.
He chaired all-party peace negotiations which led to the Belfast Agreement in 1998.
At the Belfast conference, Mr Mitchell added: “David Ervine represented in his life and in his work what I think are the best qualities of the people of Northern Ireland.
"He was very energetic, he was totally committed to the cause of reconciliation in Northern Ireland and for improving the lives of the people, especially the working class from which he came.
"He added that sense of humour and he was an inspirational leader and he was a great contributor to the peace process."
The east Belfast event was organised by the David Ervine Foundation, established after his death from a heart attack and stroke in January 2007. The Foundation helps disadvantaged children from across the community and many were present tonight.
Others included the head of the Independent International Commission on Decommissioning, General John De Chastelain, who oversaw the destruction of weapons by armed groups, and loyalist leader Gusty Spence.
Politicians from most parties were also present.