Workers have sealed off the tomb of the former Palestinian leader, Yasser Arafat, in Ramallah in preparation for the possible exhumation of his body.
Officials plan to dig up his remains in the coming weeks to allow scientists to ascertain whether his death in Paris in 2004 was caused by poisoning.
France began a murder inquiry in August after Swiss experts found radioactive polonium-210 on his personal effects.
Arafat's medical records say he had a stroke resulting from a blood disorder.
His widow, Suha, objected to a post-mortem at the time, but has appealed to the Palestinian Authority to permit the exhumation "to reveal the truth".Preparatory work
Arafat's body lies in a stone-clad mausoleum inside the Muqataa presidential compound in the West Bank city of Ramallah.
It has now been sealed off with scaffolding and blue tarpaulins to hide it from view, and roads around the compound have been blocked off, reports the BBC's Jon Donnison.
A source close to the Arafat family told the AFP news agency that workers had already started removing concrete and stones from the mausoleum.
"There are several phases," the source added. "It starts with the removal of stone and concrete and cutting the iron [framework] until they reach the soil that covers the body, which will not be removed until the arrival of the French prosecutors, Swiss experts and Russian investigators."
No date has been set for the exhumation, but the source said preparatory work would take about 15 days.
The process of taking samples is expected to begin at the end of the month, after the French and Swiss delegations arrive on 26 November.
At a ceremony to mark the eight anniversary of Arafat's death on Sunday, Palestinian Authority President Mahmoud Abbas revealed that Russia would also be assisting the investigation, although he did not say how.
"We hope for new facts that we can tell our people and the public," he said.
A murder inquiry was launched by French prosecutors in August after the Institute of Radiation Physics (IRA) at the University of Lausanne in Switzerland found "significant" traces of polonium-210 present in samples taken from Arafat's personal effects, including his trademark keffiyeh.
In some cases, the elevated levels were 10 times higher than those on control subjects, and most of the polonium could not have come from natural sources, the scientists said.
Arafat, who led the Palestine Liberation Organisation for 35 years and became the first president of the Palestinian Authority in 1996, fell violently ill in October 2004 at his compound.
Two weeks later he was flown to a French military hospital in Paris, where he died on 11 November 2004, aged 75.
In 2005, the New York Times obtained a copy of Arafat's medical records, which it said showed he died of a massive haemorrhagic stroke that resulted from a bleeding disorder caused by an unknown infection.
Independent experts who reviewed the records told the paper that it was highly unlikely that he had died of Aids or had been poisoned.