JERUSALEM >> Neither Israel nor the Palestinian Authority has formally requested U.S. assistance in the investigation into the killing of a Palestinian-American reporter during an Israeli raid in the occupied West Bank, the State Department said Wednesday.

An AP reconstruction of the May 11 killing of Al Jazeera reporter Shireen Abu Akleh lends support to Palestinian witnesses who say she was shot by Israeli soldiers. But Israel and the PA each have sole possession of potentially crucial evidence needed for any final conclusion.

Israel says Abu Akleh was killed during a complex shootout between soldiers and Palestinian militants, and that only ballistic analysis of the bullet — which is held by the PA — and the soldiers’ guns, can determine if one of them fired the fatal shot.

The involvement of a third party could overcome the severe distrust between the sides, allowing for a full and impartial account of what happened. But there’s no sign either is willing to cede control over its own investigation.

Israel has publicly called for a joint investigation with the PA, with U.S. participation.

But this week, State Department spokesman Ned Price said he was “not aware of any request for assistance” from either side. When asked during a press briefing Wednesday — two weeks after Abu Akleh’s death — if the U.S. had been asked to participate or act as an observer, he stood by his previous answer.

“We have made clear to both Israeli and Palestinian authorities that we expect the investigations to be transparent and impartial, a full, thorough accounting into the circumstances of the killing of Shireen Abu Akleh,” Price said.

Any American involvement would require a request from both Israel and the PA, which administers parts of the occupied West Bank.

Israeli Foreign Ministry spokesman Lior Hayat said “Israeli officials publicly invited the United States to be part of the inquiry.” He added that “similar messages were passed on official channels” but declined to elaborate.

The Palestinian Authority says it is carrying out its own investigation and will share the results with international parties. It has refused to hand over the bullet or cooperate with Israel in any way, saying it doesn’t trust Israel to investigate itself.

Within hours of her death, both the PA and the Qatar-based Al Jazeera accused Israel of deliberately killing Abu Akleh, but provided no specific evidence for the claim, which Israel strongly denies.

Ballistics analysis could potentially match the bullet to a specific firearm, but only if investigators have access to both. Israel and the Palestinians are unlikely to accept any conclusions reached by the other side.

Abu Akleh had spent more than 25 years covering the Israeli-Palestinian conflict. She was a widely known and respected on-air correspondent for Al Jazeera’s Arabic service, where she reported on Israel’s nearly 55-year military occupation of the West Bank. She is now seen by Palestinians as a martyr to both journalism and their national struggle.