A former senior US legal official, David Crane, will lead a UN investigation into violence in Gaza, the United Nations said on Wednesday.
At least 140 Palestinians have been killed by the Israeli army in what it has called border protection. One Israeli soldier has been killed during the weekly protests that began on 30 March.
The UN Human Rights Council voted in May to set up the probe into the killings, to the fury of Israel, which said it was being demonised.
An Israeli Foreign Ministry spokesman on Wednesday declined immediate comment.
Israel has a long history of not cooperating with UN human rights inquiries or allowing them access to Gaza.
Crane, who leads the three-person Commission of Inquiry, is a law professor at Syracuse University who the UN said had over 30 years' experience in the US federal government, including as Senior Inspector General in the Department of Defense.
"Professor Crane served as Chief Prosecutor of the Special Court for Sierra Leone from April 2002 until 15 July 2005, during which period he indicted, among others, the then-President of Liberia, Charles Taylor," a UN statement said.
His co-commissioners will be Sara Hossain, a Bangladeshi barrister who formerly worked on UN investigations into human rights in North Korea, and Kaari Betty Murungi, a board member of the Kenya Human Rights Commission and previously a legal adviser at the International Criminal Tribunal for Rwanda.
The commissioners will present a final written report in March next year.
The UN special coordinator for the Middle East peace process, Nickolay Mladenov, told the UN Security Council on Tuesday that he had visited Gaza over the past week in an urgent effort to de-escalate tensions.
"I appealed to Palestinian factions not to provoke incidents at the fence, to immediately stop the firing of rockets and mortars and to stop the incendiary kites and balloons. And I appealed to Israel to reopen the crossings, stop shelling, particularly in populated areas, and to exercise restraint towards Gaza," he said.
Over the last two weeks, however, the situation quickly spiraled out of control, nearly to a point of no return.
Intense efforts by the United Nations and Egypt had calmed the situation, Mladenov said, but only in the short-term.