Dutch investigators looking into the shooting down of Malaysia Airlines Flight MH17 over Ukraine believe that a missile fired by pro-Russian militants was behind the July 2014 incident, which led to the deaths of all 298 passengers and crew traveling from Amsterdam to Kuala Lumpur.

An unnamed source familiar with an unreleased draft of the investigative report told CNN that a Russian surface-to-air missile was used to bring down the airliner and that the device was launched from a village in separatist-controlled territory.

The Dutch Safety Board, which is leading the investigation, has apparently forwarded its report for review to other agencies, including the National Transportation Safety Board and the Federal Aviation Administration in the United States.

The document is several hundred pages long and gives a minute-by-minute timeline of Flight MH17, according to another unidentified source. It apparently pinpoints the location from where the missile was fired and identifies who was in control of the territory, concluding that the blame falls squarely on pro-Russian militants.

The Russian government, however, has staunchly denied any involvement by separatists loyal to Moscow, and local media have suggested that the Boeing 777 was shot down by a Ukrainian fighter jet, the Guardian reported.

Alexander Zakharchenko, the leader of the self-proclaimed Donetsk People's Republic that challenges the central government's sovereignty over eastern Ukraine, meanwhile, insisted that Kiev's forces were the ones to have Russian-made Buk missiles in their arsenals.

"I have said several times that we did not shoot down the Boeing," Zakharchenko said. "We never had this kind of missile system. The Ukrainian army had a Buk. And so with a calm conscience we will happily receive any mission that wants to look into it."

Nevertheless, earlier reports that Russia had doctored two satellite images so it could blame Ukraine in the crash had already fueled suspicions that Moscow may have something to hide, Bellingcat, an independent citizen journalist group, noted.

Definitive confirmation of who was behind the MH17 could have wide-ranging implications. If the attack was committed "by a country -- either directly or indirectly -- then it could be considered an act of war," said former Sen. Carl Levin, who chaired the Senate Armed Services Committee.

Beyond diplomatic squabbles, the families of those who died on Flight MH17 are still hoping for justice, Mashable reported.

"We want to find out who shot down the plane," said Ivy Loi, whose husband was one of the pilots. "We must find out."