Military officer Oleg Ivannikov's unusual voice helped investigators pinpoint him as a key suspect.
The families of the dead have published an emotional open letter.
Vladyslav Voloshyn, 29, killed himself at his home on Sunday.
International investigators reported on Wednesday that a Russian missile downed the jet.
The Ministry of Foreign Affairs said Moscow is the only credible source of information.
Investigators told the victims’ families that the rocket was fired from rebel-held ground.
Investigators are said to be looking at a wide range of possible suspects.
Digital forensics prove that Russian-backed separatists brought down the Boeing 777 over eastern Ukraine.
In a press conference held today, investigators said that those on board were likely to have died instantly.
The Dutch Safety Board is expected to say it was downed by a Russian-made Buk missile but not say who was responsible for firing it.
The speaker of parliament called a proposed tribunal into MH17 a "political provocation."
Putin’s Security Council veto shows how isolated Moscow has become one year after the MH17 tragedy.
Russia continues to reject a U.N.-backed tribunal.
"It is most likely that Flight MH17 was destroyed in mid-air by the impact of a 9M38M1 surface-to-air missile."
The remains of 296 of 298 of those on board have been identified.
NATO says airspace incursions are up 300% this year in dangerous return to Cold War tactics that could risk MH17-style disaster
The Russian government has always said it has radar imagery proving the fully laden Boeing 777 was shot down by a Ukrainian military aircraft flying in its vicinit
Comments from the head of Germany's BND mark the first time an intelligence agency has pointed the finger at any one side over the disaster
Two-thirds of the victims were Dutch nationals and the Dutch Safety Board is in charge of the investigation into how the Boeing 777 was downed
Australian PM Tony Abbott said he will use an upcoming summit to confront the Russian president over the downing of Malaysia Airlines flight MH17
The MH17 and MH370 disasters have only compounded a bad financial situation for the airline, and now staff are facing cuts as a result
A minute's silence was held across Malaysia to mark the return of the first 20 bodies of victims of the downing of MH17