Early in 2021, Assad, who was 80 years old, suffered a stress-induced heart attack after he was arbitrarily detained, bound, blindfolded and gagged by Israeli forces, and then left out unresponsive on the ground at a cold construction site in the occupied West Bank.

The Israeli army said on Tuesday that it found no “causal link” between the way its soldiers treated Assad and the American citizen’s death.

The US Department of State, which often reiterates that the safety of Americans abroad is its top priority, said on Wednesday that it was looking into the Israeli findings.

“We’re aware of the conclusion of the investigation, and we’re at this time seeking more information from the Israeli government about it,” State Department spokesperson Matthew Miller told reporters. “We’re going to talk to them directly about it.”

Miller said Washington expected “full accountability” in the case early on.

“We have been clear about our deep concern on the circumstances surrounding Omar Assad’s death and the need for such accountability,” he added.

Leahy Law

Assad was one of two US citizens killed by Israel last year – the other, Al Jazeera journalist Shireen Abu Akleh, was fatally shot by Israeli forces while covering a raid in Jenin in the occupied West Bank.

Israeli authorities rarely ever prosecute abuses by their forces against Palestinians, but the US vehemently opposes Palestinians’ efforts to seek accountability at the International Criminal Court, including in the case of Abu Akleh.

Israel, accused of imposing a system of apartheid by leading human rights organisations like Amnesty International, receives at least $3.8bn of US aid annually.

President Joe Biden and his top aides often stress Washington’s “ironclad” commitment to Israel.

Adam Shapiro, director of advocacy for Israel-Palestine at Democracy for the Arab World Now (DAWN), a US-based rights group, called for meaningful accountability for the killing of Assad.

He said the Biden administration should apply the Leahy Law, which bans American aid to foreign forces engaged in gross violations of human rights, to Israel’s Netzah Yehuda unit that was involved in the killing of Assad.

Shapiro added that the State Department has been looking at the case from the perspective of the Leahy Law after DAWN submitted a referral to the US government last October, which underscored that the blindfolding of Assad violated Israeli regulations.

“We believe that that process should not only continue, but that this closure of the Israeli investigation requires the State Department to now apply Leahy Law sanctions to the unit,” Shapiro told Al Jazeera.

He added that by blindfolding Assad, Israeli soldiers “took an action that was deliberate and intentional that was a violation of their own rules”. He said the Palestinian autopsy report on the death of Assad noted that the gagging and blindfolding of the elderly US citizen contributed to his heart attack.

“We have a direct line of causation from the deliberate illegal actions by the Israeli soldiers to the death of Assad,” Shapiro said.

‘Same message’

For his part, Osama Abuirshaid, executive director of American Muslims for Palestine (AMP), raised concern about the State Department statement on Wednesday.

“It’s the same message – ‘We’re following up; we’re in touch with our Israeli counterparts; we are demanding an investigation by the Israelis.’ But when the outcome of an investigation is released, and it does not meet the expectations, we don’t see an American response,” Abuirshaid told Al Jazeera.

In February 2022, Washington welcomed an Israeli report that said the death of Assad “showed a clear lapse of moral judgment” and announced disciplinary action against the commander of the Netzah Yehuda unit.

“The United States expects a thorough criminal investigation and full accountability in this case,” the State Department said at that time.

Abuirshaid said that if the Biden administration does not impose consequences on Israel for killing Assad, it would be abdicating its responsibility to protect US citizens.

“Our problem is not only with Israel and its mistreatment of American citizens, but our problem is mainly with our own administration – with our own government here – that allows Israel to continue its mistreatment of American citizens,” Abuirshaid said, also citing the killing of Abu Akleh.