The Federal Bureau of Investigation has launched an investigation into the killing of Palestinian-American Al Jazeera journalist Shireen Abu Akleh in May, Israeli media reported on Monday.

In September, the IDF concluded its own investigation into the death of Abu Akleh, who was killed during a firefight between Israeli forces and Palestinian gunmen in Jenin. The IDF stated at the time that “it appears that it is not possible to unequivocally determine the source of the gunfire which hit Ms. Abu Akleh. However, there is a high possibility that Ms. Abu Akleh was accidentally hit by IDF gunfire that was fired toward suspects identified as armed Palestinian gunmen, during an exchange of fire in which life-risking, widespread and indiscriminate [fire was directed] toward IDF soldiers.”

The IDF had added that the possibility of Abu Akleh being hit by Palestinian fire “remains relevant.”

On Monday, Israeli Defense Minister Benny Gantz said Israel would not cooperate with the FBI’s probe or any external investigation into the killing of Abu Akleh.

“The U.S. Justice Ministry’s decision to investigate the unfortunate death of Shireen Abu Akleh is a serious mistake,” Gantz said in a statement.