“Ballistic experts determined the bullet was badly damaged, which prevented a clear conclusion,” according to a statement on Monday.
The US Security Coordinator, by summarising investigations by both Israel and the Palestinian Authority, also said on Monday that the detailed forensic analysis showed no reason to believe that the shooting was intentional.
Abu Akleh was shot in the head on May 11 while covering an Israeli army raid on the Jenin refugee camp in the occupied West Bank, despite wearing a flak jacket and helmet clearly marked “PRESS”.
Palestinian officials, international rights groups and media outlets, carried out independent investigations that concluded that Abu Akleh was killed by the Israeli military.
The United Nations human rights office last month stated that information it had gathered showed that the bullet that killed Abu Akleh was fired by Israeli forces. Several eyewitnesses said Israeli forces killed the Jerusalem-born Abu Akleh.
A senior Palestinian official accused the United States of protecting Israel after the forensic examination failed to reach a firm conclusion on the origin of the bullet that killed Abu Akleh.
“The truth is clear but the US administration continues to stall in announcing it,” Wasel Abu Youssef, a member of the Executive Committee of the Palestine Liberation Organisation (PLO), told Reuters news agency.
“We say Israel killed Shireen Abu Akleh and it has to be held responsible for the crime it has committed,” Abu Youssef added.
On Saturday, Akram al-Khatib, general prosecutor for the Palestinian Authority, said that officials had “agreed to transfer the bullet to the Americans for examination”.
However, conflicting reports over who would conduct the tests on the bullet emerged on Sunday, with an Israeli military spokesman telling Army Radio, “The test will not be American. The test will be an Israeli test, with an American presence throughout.”
The State Department statement came just weeks before an expected visit by US President Joe Biden to Israel and the West Bank.