The Dutch government has refused to turn over the investigation into the crash of Malaysia Airlines Flight 17 to the United Nations.

The Associated Press reported that some of the victims' families have filed a lawsuit because they said the investigation into the crash, which occurred in mid-July, is taking too long.

Flight 17 was shot down July 17 while flying over Ukraine near the border of Russia, where pro-Russian rebels reside. All 298 passengers and crew members on board–most of whom were Dutch–died.

Since then, the investigation into the crash has been fraught with delays.

At first, there was criticism over the handling of the bodies, since international aid workers had problems reaching the site. Their efforts were constantly interrupted by the clashes between the rebels and military.

Six bodies have yet to be identified.

After the bodies were taken away, the plane debris has been stuck in the area for months.

Huge chunks of the aircraft finally reached the Netherlands this week by truck.

"We are doing what we can, and we do it every day anew," Security and Counterterrorism Coordinator Dick Schoof said in a statement.

Exactly what caused the crash of the plane over the disputed territory remains unknown, and various news sites have reported different things.

RT reported that the Dutch Safety Board was open to the suggestion of a military plane being involved.

AP reported the Dutch Safety Board issued a preliminary report in September that the plane was brought down by "high-energy objects from outside the aircraft."

Other news sites suggested a missile launched from the ground soon after the crash.

"For the Cabinet, it is of the utmost importance that the independent investigations indisputably determine what happened and that no one can dispute the conclusions ... or say that the Netherlands as leader gave cause to doubt the independence of the investigation," Schoof said.

The board anticipates several more months until a final report can be released.