Police in Croatia have arrested six former soldiers on suspicion of war crimes against ethnic Serbs.
The six have been accused of detaining and killing Serbian civilians in the town of Osijek in eastern Croatia in late 1991 and early 1992.
A number of Serbs were found dead in the river with their hands and feet tied as the four-year conflict between Croatian and Serbian forces began.
Human rights groups have been pressing for the killings to be investigated.
Osijek county police chief Vladimir Faber announced that five men and one woman, all former members of a paramilitary unit, had been detained.
"Finally, after 15 years we have resolved the killings of civilians in Osijek," he said.
Thirty-seven Serb civilians were killed in Osijek over the period in question, according to police figures.
Osijek was heavily shelled by rebel Serbs and the Yugoslav army at the beginning of the war, which was triggered when Croatia declared independence from the former Yugoslavia.