An Austrian human rights lawyer and others on Monday blamed the slaying of a Chechen refugee on the president of the southern Russian republic and expressed hope that an upcoming trial will help prosecute him.

Umar Israilov, 27, was shot dead on a street in Vienna in January 2009. Austrian investigators and activists have alleged the killing was linked to Israilov's opposition to Chechnya's pro-Kremlin leader, Ramzan Kadyrov. In August, prosecutors charged three men in the slaying but said there was not enough evidence to charge Kadyrov.

The trial starts Tuesday. Before the proceedings, Vienna lawyer Nadja Lorenz said she and her supporters will present evidence linking the defendants to Kadyrov, known for his strong-arm rule.

"This will lay the foundation for holding Kadyrov accountable later — that's what we're working toward," said Lorenz alongside other human rights proponents amid tight security. "We have to use whatever legal means we have to stop the torturers of this world."

The accused — being held in pretrial custody in the Austrian capital — have been charged with, among other things, accessory to murder when an attempt to kidnap Israilov went awry. A fourth man who fired the fatal shots is at large.

This spring, Austrian investigators concluded that Kadyrov — a former Chechen separatist rebel — ordered the kidnapping of Israilov, who used to be one of this bodyguards. At the time, the Vienna public prosecutor's office said the findings were based on circumstantial evidence including a photograph of Kadyrov and the main defendant, identified as Otto Kaltenbrunner, that was found on Kaltenbrunner's cell phone.

The prosecutor's office also confirmed at the time that investigators had found a connection between Kaltenbrunner and Shaa Turlayev, a close adviser to the Chechen leader.

According to the Berlin-based European Center for Constitutional and Human Rights, Israilov — who was the father of four children — had reported that he had been repeatedly tortured by Kadyrov and had served as a chief witness in court proceedings against Russia before the European Court of Human Rights. His accounts had also formed the basis of a criminal complaint against Kadyrov on charges of torture and attempted duress filed by Austrian lawyers in June 2008.

"Kadyrov's guards forced me to sit on an exercise machine and attached one cable to my ear and another to my little finger," the center quoted Israilov as saying. "Then, Kadyrov began turning the crank handle which delivered an electric shock. I felt an awful pain in my head and hand."

He also recalled being stabbed in the legs with a metal rod as thick as a finger and said he had witnessed "numerous accounts of systematic torture and unlawful executions conducted by Kadyrov and his associates."

Lorenz and Wolfgang Kaleck, secretary general of the European Center for Constitutional and Human Rights, criticized Austrian authorities for not granting Israilov police protection although he had asked for it.

"Austrian authorities disregarded the European and international dimension of this case from the very beginning," Kaleck said, adding that "much remains to be clarified."

When asked whether good relations between Austria and Russia may have played a role in the fact that Kadyrov was not charged, Lorenz said: "Of course that's a political question, and of course Austria doesn't want any problems with the Russian Federation," she said.

Heinz Patzelt, head of Austria's chapter of Amnesty International, said he saw the trial as a key chance to establish evidence against Kadyrov that could then be used as a "very important jigsaw piece" in other, larger proceedings against him.

"There's an enormous responsibility on the judge, on the jury, on the public prosecutor, to raise the right questions and to give very brave answers," Patzelt said.

(This version CORRECTS attribution to 'Israilov' in ninth paragraph, adds quote from lawyer, detail on tight security.)