Four former members of a Serbian paramilitary force were convicted Friday of abducting 16 Muslims from a bus in 1992 and taking them to Bosnia to be tortured and executed.

The court said the four former members of the Avengers paramilitary group abducted 15 Muslim men and a woman while they were traveling from Serbia to their work in neighboring Bosnia in October 1992 and took them to a nearby motel where they were tortured with knives and then executed on the banks of the Drina River, on the border between Serbia and Bosnia.

Their bodies have not been found. Photographs of the victims, believed to be made by the culprits that night, were used as the main evidence against the four. The high-profile trial was intended to show that the Serbian judiciary can deal with war crimes cases impartially.

The two in custody, Djordje Sevic and Dragutin Dragicevic, got 15 and 20 years respectively. Two others, Milan Lukic and Oliver Krsmanovic, are on the run and were tried in absentia, and received 20-year jail terms — half the maximum sentence.

Lukic is among the top war crimes suspects wanted by the U.N. war crimes court in The Hague, Netherlands. The U.N. tribunal has charged him with a similar abduction and the killing of 20 Muslims from Serbia in 1993.

Relatives of the victims said the sentences should have been harsher.

"If one man kills another, he gets 10 years in jail," said Vula Djodzgic, the sister of one of the victims. "Here we had 16 people killed in an unspeakably brutal way. The trial again failed to reflect the scope of this monstrosity."

War crimes trials in Serbia became possible only after the 2000 toppling and subsequent handover to the U.N. war crimes court of the autocratic ex-President Slobodan Milosevic, now on trial for genocide.

Milosevic's government is believed to have backed several Serb paramilitary groups during the Balkan wars of the 1990s.

PHOTO CAPTION

Bosnian Muslim woman, survivor of the 1995 Srebrenica massacre, waits to bury her son during the ceremony commemorating the 10th anniversary of the massacre. (AFP)