Israel says it will test a bullet that killed Palestinian-American journalist Shireen Abu Akleh to determine whether one of its soldiers shot her.
The Israeli military says a US observer would be present for the procedure that could deliver results within hours.
The Palestinians, who on Saturday handed over the bullet to a US security coordinator, said they had been assured that Israel would not take part in the ballistics.
Washington has yet to comment. The United States has a holiday weekend to mark July 4.
The May 11 death of the Al Jazeera reporter during an Israeli raid in the occupied West Bank, and feuding between the sides as to the circumstances, have overshadowed a visit by US President Joe Biden due this month.
The Palestinians accuse the Israeli military of killing her deliberately. Israel denies this, saying Abu Akleh may have been hit by errant army fire or by one of the Palestinian gunmen who were clashing with its forces.
“The (ballistic) test will not be American. The test will be an Israeli test, with an American presence throughout,” said Israeli military spokesman Brigadier-General Ran Kochav.
“In the coming days or hours it will be become clear whether it was even us who killed her, accidentally, or whether it was the Palestinian gunmen,” he told Army Radio. “If we killed her, we will take responsibility and feel regret for what happened.”