There are "strong indications" that Russian President Vladimir Putin personally approved the supply of the missile that shot down Malaysia Airlines flight MH17 in 2014, international investigators said on Wednesday.
But the investigators said they were halting their eight-year probe, since Mr. Putin has immunity as head of state and there is not enough concrete evidence to prosecute him or other suspects.
All 298 people on board were killed when a Russian-made missile slammed into the plane travelling from Amsterdam to Kuala Lumpur, sending it crashing to earth in separatist-held eastern Ukraine.
The announcement comes less than three months after a Dutch court convicted two Russians and a Ukrainian in absentia over the downing of MH17.
"There are strong indications that a decision was made at presidential level, by President Putin, to supply the DPR (Donetsk People's Republic) with the Buk TELAR" missile system, Dutch prosecutor Digna van Boetzelaer told a news conference in The Hague.
"Although we speak of strong indications, the high bar of complete and conclusive evidence is not reached."
Dutch Prime Minister Mark Rutte said the decision was a "bitter disappointment" but that "we will continue to call the Russian Federation to account for its role in this tragedy".
Russia has denied any involvement in the downing of MH17. It slammed last year's court verdict convicting the three men as "scandalous" and politically motivated.
But the five-country Joint Investigation Team into the crash of MH17 said the chain of command was clear.
Russian officials even postponed a decision to send weapons to Ukrainian separatists because Mr. Putin was at a D-Day commemoration in France in June 2014, they said.
They played an intercepted telephone call from an advisor saying the delay was "because there is only one who makes a decision (...), the person who is currently at a summit in France".
Other officials such as Russian Defence Minister Sergei Shoigu did not have the necessary decision-making power and "this was ultimately the president's decision", they said.
However, with a lack of cooperation from Moscow and a dearth of witnesses willing to come forward, the case has now ground to a halt.
"All leads have now been exhausted, the investigation is therefore being suspended," van Boetzelaer said.
Mr. Putin himself was untouchable — for now at least.
"The President of the Russian Federation enjoys, at the very least, immunity under international law in view of his position as head of state," added the Dutch prosecutor.
"Only after he is head of state we can look into what's next."
The victims of the disaster — which triggered international outrage and sanctions against Russia — came from 10 countries, including 196 Dutch, 43 Malaysians and 38 Australian residents.
Investigators admitted there was "disappointment" among next of kin at the decision to halt the probe.
"Of course there was disappointment. They wanted to know why MH17 was shot down... the answer remains in Russia," said Andy Kraag, head of the Dutch National Criminal Investigation Department.
Investigators themselves had also "wanted to go further", he added.
But the team said they were satisfied they had at least brought three suspects to justice and investigated others as far as they could.
"The disappointment would settle on us I think if we felt we hadn't done all we could do," said David McLean, Assistant Commissioner of the Australian Federal Police.
The MH17 probe has not closed and will keep its hotlines and website open, officials added. The evidence it has gathered could also be used by other tribunals including the International Criminal Court, it said.
The three men convicted last year — Russians Igor Girkin and Sergei Dubinsky and Ukrainian Leonid Kharchenko -- remain at large and are unlikely to ever serve their life sentences.
Girkin has since become a high-profile critic of Russia's military policy in Ukraine, criticising earlier retreats by Moscow's troops.