Dutch prosecutors said Wednesday that it was likely Russian President Vladimir Putin personally signed off on a decision to supply long-range antiaircraft missiles systems to pro-Russian separatists in eastern Ukraine before they shot down Malaysia Airlines Flight 17 in July 2014, killing all 298 passengers and crew.

Vladimir Putin

However, while the prosecutors said they had documented “strong indications” of Putin’s personal role in the decision, they said their evidence “was not concrete enough” for a new prosecution.

In November, two former Russian state security officers and a Ukrainian separatist leader were convicted of murder in the case, though they were never arrested or extradited. Dutch authorities have been in charge of the investigation because the flight originated in Amsterdam.

The Joint Investigation Team led by the Dutch had previously determined that a Russian-supplied Buk surface-to-air missile hit the Boeing 777 flying to Kuala Lumpur on July 17, 2014, killing all passengers and crew.

At a news conference in The Hague on Wednesday, the Joint Investigation Team said its conclusions about Putin’s personal role rested on recorded telephone conversations in which Russian officials say that the decision to provide military support could be made only by the Russian president.

“There is concrete information that the separatists’ request was presented to the president, and that this request was granted,” the investigators said, adding that “it is not known whether the request explicitly mentions a Buk system.”

The team noted that despite the strong indication, “the high bar of complete and conclusive evidence is not reached” and that Putin, as the head of the country, enjoys immunity from prosecution. The prosecutors said that they had exhausted their leads and that there would be no more criminal proceedings.

In its November verdict, a Dutch court convicted three suspects of murder, though none of them are in custody. A fourth suspect was acquitted. The verdict offered a concrete determination that Moscow bore responsibility for the downing of the plane.

The Kremlin has long denied any involvement in the destruction of the jetliner and has refused to extradite the defendants or cooperate with investigators.