The Iraqi investigation found that convoys from Blackwater did not come under direct or indirect fire when the private guards opened fire on a busy intersection, as the firm has claimed.
The report also raised the number of Iraqis killed to 17, up from a previous estimate of 11 deaths.
An Iraqi government spokesman said the Iraqi cabinet would weigh the Iraqi findings with those of a joint U.S.-Iraqi commission "and subsequently adopt the legal procedures to hold this company accountable."
The September 16 shooting was one of at least six fatal incidents allegedly caused by Blackwater that Iraqi authorities have brought to the attention of the United States.
(AP)