Relatives of the victims complained to the court in 2007 that the Russian inquiry had been ineffective and that the Russian authorities had displayed a dismissive attitude to requests for information about the event. The case was brought by 15 Polish citizens who are relatives of 12 victims of the massacre — police and army officers, an army doctor and a primary school headmaster — according to court filings.

The court’s highest panel, the Grand Chamber, ruled unanimously that “Russia had failed to comply with its obligation” under the European Convention on Human Rights to “furnish necessary facilities for examination of the case,” according to a statement from the court in Strasbourg, France.

But the ruling said the court had no jurisdiction to examine complaints over the killings themselves because the massacre took place a decade before the rights convention became international law and 58 years before Russia acceded to it, in 1998.

That period was too long for a “genuine connection” to be established between the killings and Russia’s accession to the convention, the ruling said. The court rejected an application for awarding damages.

The court also ruled that there had been no violation of the convention’s provision prohibiting inhuman or degrading treatment as it relates to the suffering of families of “disappeared” people. That part of the ruling overturned a lower court’s ruling in 2012, which found that that provision had been violated in the cases of 10 of the 15 Polish family members.

In its ruling, the Grand Chamber said Russia had not offered a “substantive analysis” for keeping the decision to close its investigation classified. “The court was unable to accept that the submission of a copy of the September 2004 decision could have affected Russia’s national security,” the ruling said.

Nikita V. Petrov, a historian for the Memorial human rights group, which has sought to declassify the decision, called the ruling a “light reprimand” that would do nothing to further the investigation.