The State Department said US ambassador to Israel Daniel Kurtzer had received a copy of an internal Israeli Defense Forces (IDF) investigation ten days after the March 16 incident that determined Rachel Corrie's death was an accident.
"The report indicates that Ms Corrie's death was the result of a bulldozer operation but that the driver was unaware of her presence on the site," said Lynn Cassel, a department spokeswoman.
"We do not consider this matter closed with the reception of the internal IDF report," she said. "We are going to press for a full and transparent investigation."
Cassel declined to comment on whether the United States believed the Israeli account, but pointedly noted that US officials had raised a series of questions about it and asked Israel for additional information about the incident.
"We have asked Israeli officials a number of questions about the account in the report," she said. "We have also asked for the audio and video-taped recordings made by the IDF before, during and after incident.
"We will continue to assess information as it is developed and remain in close contact with senior Israeli officials," Cassel said.
She added that Washington was still awaiting the results of a full autopsy on Corrie and noted that another investigation, this one conducted by the IDF's advocate general, was now underway and could lead to criminal prosecutions should it uncover any wrongdoing.
Corrie, 23, from Washington state, was killed in Rafah, close to the Israeli-controlled border in the Gaza Strip (news - web sites), while trying to prevent army bulldozers from destroying Palestinian homes, hundreds of which have been razed since the start of the intifada in September 2000.
Fellow peace activists who witnessed the incident have accused the army of deliberately killing her, while the army has maintained her death was accidental and has taken no action against the bulldozer driver.