KIEV, Ukraine — A Dutch-led investigation team said Wednesday that the surface-to-air missile that downed a passenger jet over eastern Ukraine in 2014, killing all 298 people aboard, came from Russia and was fired from territory held by pro-Moscow separatists.

Investigators stopped short of directly accusing Russia of complicity in the attack on the Malaysia Airlines jet, and declined to name any suspects publicly. Both Russia and the rebels in Ukraine deny any role in the July 2014 attack on Flight 17, which was traveling from Amsterdam to Kuala Lumpur.

The findings are intended to be used in a possible criminal trial. But even if the guilty are identified, it’s unclear how they would be apprehended, especially if they are located in Russia or in separatist-held Ukraine.

The SA-11 "Gadfly” system thought to be used in the missile firing — four surface-to-air missiles mounted on a launch vehicle — was smuggled into Ukraine from Russia just hours before the missile was fired, the investigators said at a news conference in Amsterdam. The system, also known as a BUK trailer, was returned to Russia the day after the attack, which left bodies and wreckage strewn across farms and fields of sunflowers.

The evidence was based on intercepted telephone conversations between separatist fighters in eastern Ukraine, as well as open-source photographs and satellite data, investigators said.

"It may be concluded that Flight MH17 was shot down on 17 July 2014 by a 9M38 series missile launched from a BUK trailer. This BUK trailer was brought in from the territory of the Russian Federation and after launch was subsequently returned to Russian Federation territory. This conclusion is based largely on forensic investigation,” said Wilbert Paulissen, a senior investigator in the Dutch national police.

The team members said that they had identified more than 100 people linked to the transport of the missile system and that they would seek to identify "who ordered the plane to be shot down.” The investigation has been extended into 2018.

No venue has been given for a possible trial, and a successful prosecution probably will depend more on diplomatic wrangling than the dogged gathering of facts.

Moscow has maintained that it has not backed the separatists at all, much less supplied them with a modern anti-aircraft missile system that requires a trained crew to operate. On Monday, Russia said it had radio-location data that implicated Ukraine’s government in the attack, and ruled out the launch of a missile from separatist-held territory.

In Ukraine, separatist leaders on Wednesday denied the evidence presented in the report, saying that they did not have access to sophisticated surface-to-air missiles, and accused Ukraine’s government of the attack.

Dutch investigators indicated Wednesday that the BUK may have been transferred to Ukraine to protect separatists from Kiev’s aerial attacks during pitched fighting in the summer of 2014.

The investigators, citing intercepted telephone calls and social media photos, said that the trailer carrying the BUK missile system crossed into Ukraine from Russia on the morning of July 17, the day of the attack, accompanied by a jeep and minivan carrying separatist fighters. Video and photographs showed the missile system that day in Donetsk, the largest city held by the separatists, and then traveling toward the villages of Snizhnoye and Pervomaiskiy.

The missile "without any doubt” was launched from a field in the farmland near Pervomaiskiy, a video made by the investigators said, citing witnesses who gave testimony and pictures of a smoke-trail coming from the fields.

The missile launcher was subsequently driven back across the Russian border early the next morning on a Volvo truck, based on videos and intercepted telephone calls, the investigators said.

The Dutch-led investigation includes representatives from Australia, Belgium, Malaysia and Ukraine. Relatives of those killed in the attack were informed of the conclusions earlier Wednesday. Of the victims, 193 were Dutch citizens, 43 were from Malaysia and 27 were from Australia. Citizens of the United States, Belgium, Britain, Canada, Germany, Indonesia, New Zealand and the Philippines also died in the crash.

Agencies