Investigators probing the downing of a Malaysia Airlines jet in eastern Ukraine in which 298 people died in 2014 are expected to name suspects.
The Dutch-led Joint Investigation Team (JIT) will present new evidence and announce charges for the first time.
Relatives of those killed on the plane said they had been told that four men would be charged with murder.
Passenger flight MH17 was en route from Amsterdam to Kuala Lumpur when it was shot down over conflict-hit Ukraine.
Investigators blame Russian-backed separatists who they say targeted the plane with a Russian-made missile.
The Boeing 777 crashed in rebel-held eastern Ukraine on 17 July 2014, at the height of the conflict between government troops and separatists.
Russia has denied any involvement and has maintained the missile was fired from Ukrainian-held territory.
Kremlin spokesman Dmitry Peskov told the BBC on Wednesday that Russia had been given "no chance to take part" in the official investigation.
Asked whether Russia would hand any suspects over for trial, Mr Peskov said Moscow's position was "very well known", but declined to comment further.
What will investigators say?
Dutch investigators will hold a press conference at 13:00 local time (11:00 GMT) on Wednesday after briefing relatives of victims.
Relatives who were briefed before the press conference said three Russians and a Ukrainian would be charged with murder ahead of a trial in March 2020.
They told reporters the men included ex-rebel leader Igor Girkin, also known as Igor Strelkov.
Kateryna Zelenko, a spokeswoman for Ukraine's foreign ministry, said earlier that "the guilt of the four suspects must be proved first and foremost in court".
The JIT, which seeks to try the suspects under Dutch law, has previously said it had a "long list" of persons of interest and appealed for witness help.
On Friday, prosecutors announced the release of new findings, prompting widespread reports in Dutch media that suspects will be named.
On Wednesday, internet open source investigators Bellingcat released a new report into the crash further detailing its assessment of individuals it alleges were involved in the transportation of a Buk missile used in the downing of MH17.
Among the 12 people named are Igor Girkin, the former military leader of pro-Russian rebels in the eastern Ukrainian city of Donetsk, and separatist leader Igor Bezler, who was previously identified in voice recordings of phone conversations that took place shortly after the plane was shot down.
In earlier reports, the Bellingcat team has alleged that a military intelligence colonel in the rebel-held Donetsk area known as Khmuryi (gloomy) and a military intelligence official commanding Russian-backed separatists in Luhansk who went by the codename of Orion were also involved.
Hans de Borst, whose 17-year-old daughter Elsemiek was on board flight MH17, told the BBC's Anna Holligan that he hoped investigators would expose the truth and that naming suspects would be a "first real step towards justice".
Silene Fredriksz, who lost her son Bryce, said that in the five years since the tragedy, some relatives had died not knowing the truth.
"I hope the trial starts within one or two years. We all get older... I hope that I will know the truth before I close my eyes."
What is known about the crash?
MH17 left Amsterdam's Schiphol Airport at 10:15 GMT on 17 July 2014 and was due to arrive at Kuala Lumpur in Malaysia the following day.
About four hours after take-off, the plane lost contact with air traffic control about 50km (30 miles) from the Russia-Ukraine border.
The plane crashed in the Donetsk area, in territory controlled by separatists. Parts of the wreckage were found distributed over an area of about 50 sq km.
In October 2015 the Dutch Safety Board concluded the plane had been hit by a Buk missile, causing it to break apart in mid-air.
In 2016, the JIT - which includes officials from the Netherlands, Australia, Belgium, Malaysia and Ukraine - reached a similar conclusion.
The Dutch-led team concluded in May 2018 that the missile system belonged to the 53rd Anti Aircraft Missile brigade, based in the western Russian city of Kursk. It produced evidence it said proved how the missile system reached Ukraine.
Russia responded by denying any of its anti-aircraft missile systems had ever crossed the Ukrainian border. Its foreign ministry has accused the JIT investigation of being "biased and politically motivated".
A total of 283 passengers, including 80 children, and 15 crew members were killed on the flight.
Delays and difficulties in the recovery of victims' remains in the crash aftermath prompted widespread international criticism.