NIEUWEGEIN, Netherlands (AP) -- A man whose daughter died when a Malaysia Airlines plane was shot down over Ukraine said families were told Wednesday that a Dutch-led investigation has found proof that a mobile Buk missile launcher had been moved into eastern Ukraine from Russia at the time.
Hans de Borst, whose 17-year-old daughter perished, said he and other family members were briefed privately Wednesday morning before a news conference scheduled to announce the preliminary results of the investigation.
Investigators said they had proof, including communications intercepts and radar data, that a mobile Buk missile launcher had been moved into eastern Ukraine from Russia, then was returned after the Boeing 777 was destroyed, de Borst said.
The conclusions were billed as results of a two-year Dutch-led criminal probe of the disaster that claimed 298 lives.
Thomas Schansman, father of the only U.S. citizen killed in the July 2014 disaster, said earlier that he expected investigators to identify which specific weapon they believe destroyed flight MH17, and where it was fired from. He said family members do not expect investigators at this stage to name the people they believe were responsible.
A separate investigation by Dutch safety officials last year concluded that the Amsterdam-to-Kuala Lumpur flight was downed by a Buk missile fired from territory held by pro-Russian rebels.
Dutch police spokesman Thomas Aling said the joint investigation findings differ in that they are designed to be solid enough to be used as evidence in a criminal trial. Where and when a trial might take place is still to be determined, Aling said.
Russia has consistently denied allegations that pro-Moscow rebels in eastern Ukraine were responsible. On Monday, the Russian military said it has new radio-location data that show the missile that downed the Boeing 777 did not originate from rebel-controlled territory, and said it would turn the data over to investigators.
Kremlin spokesman Dmitry Peskov reiterated that assertion on Wednesday ahead of the Dutch report.
"If there was a rocket it could only have been launched from a different area," he told reporters, referring to Russian radar data. "You can't argue with it, it can't be discussed."
In the Joint Investigation Team, Dutch police and judicial officials have been working with counterparts from Australia, Belgium, Malaysia and Ukraine, seeking to gather the best possible evidence for use in prosecution of the perpetrators.
They have faced extraordinary challenges: the crime scene in Ukraine's eastern Donetsk oblast where the plane crashed on July 17, 2014, killing all aboard, was located in an active war zone, and during the days following the crash pro-Kremlin militants limited access to the site.
Eleven containers crammed with debris from the jetliner were ultimately brought to the Netherlands. A research team took soil samples in eastern Ukraine and established the location of cellphone towers and the layout of the local telephone network.
Forensic samples were taken from passengers' and crew members' bodies and luggage, and satellite data and communications intercepts were scrutinized. The team also appealed for information from witnesses who may have seen the missile launch.
About two-thirds of the passengers aboard MH17 were Dutch nationals; the crew members were Malaysians. Malaysia proposed setting up an international tribunal to try those responsible for the plane's destruction, but Russia vetoed a U.N. Security Council resolution in favor of a tribunal.