Israel's Turkel Commission has an international observer with a formidable track record on conflict resolution in Nobel Peace Prize winner Lord Trimble.
The 65-year-old is widely admired for his role in the Good Friday Agreement, which brought peace to Northern Ireland.
The former Ulster Unionist Party leader, now Conservative Party peer, has in the past urged Israel to stand firm on Hamas.
Lord Trimble is a member of the Friends of Israel advocacy group founded by Dore Gold, a close adviser to Binyamin Netanyahu, and in 2007 chaired a House of Commons conference debating possible measures to be taken against Iran.
He made his first visit to Israel in 2000 as First Minister.
It is thought Tony Blair suggested him for the role of observer, but support has been far from universal.
Nobel laureate Mairead Corrigan Maguire has called on Lord Trimble to reconsider his role in the investigation, while Labour MP Andy Slaughter said his inclusion is "the basis for a whitewash".
Despite his considerable achievements, no role has been found for him in Britain's new coalition government.
Meanwhile, Canadian Ken Watkin has no known positions on the Middle East conflict.
The 56-year-old is a retired military lawyer with more than 25 years of experience in virtually every aspect of martial justice.
Earlier this year, Mr Watkin, who lives in Ottawa, ended a four-year term as a brigadier-general and Judge Advocate General (JAG) of the Canadian Armed Forces.
The JAG is the legal adviser to the Minister of Defence on all matters relating to military law, and is also in charge of the military justice system.
In 1993, Watkin investigated the killing of a Somali youth by Canadian soldiers in Somalia. Since 1995, he has been involved in a number of international inquiries into the 1994 genocide in Rwanda.