LANCOVO, Slovenia, Oct 22 (Reuters) After digging for two hours in a chilly forest clearing, the workers had their evidence: bones and the soil-covered, blackened remnant of a shoe confirmed this was a secret mass grave from World War Two.
In the trees a short distance from where the diggers worked, an elderly man looked on. He would not give his name, but said he had been at the same spot when he was 16, one morning in 1945, after he heard shouting in the night.
The Lancovo grave is one target of a Slovenian government programme to help people come to terms with a hidden legacy of unprecedented slaughter during the war.
So far, 540 such sites have been registered across Slovenia.
They are believed to hold up to 100,000 bodies.
''The killings that took place here have no comparison in Europe. In two months after the war, more people were killed here than in the four years of war,'' said Joze Dezman, a historian who heads the committee for registering hidden graves.
''Srebrenica is like an innocent case compared to that,'' he said, referring to the Bosnia Serb army's execution in 1995 of about 8,000 displaced Muslim civilians in Bosnia, their corpses bulldozed into the earth.
Those killed in Slovenia were mostly soldiers who collaborated with the Nazis. Most were executed in the woods without trial.
They were victims of a vengeful killing spree by Yugoslav leader Josip Broz Tito's partisans after British-led Allied troops turned them back from Austria and handed them over.
Slovenia, now a European Union country of 2 million people, declared independence from Yugoslavia in 1991, but the graves remained a public secret until excavations in recent years.
''These killings took place in Slovenia because this is where the war was ending: this is where the iron curtain was anticipated, this is where refugees found themselves at the end of the war,'' said Dezman.
The graves' existence has been quietly known for decades, but some elderly people are still too afraid of reprisals to speak about them. In Lancovo, the anonymous onlooker shared a distant memory of what he saw as a youth.
''There was blood and remnants of burnt clothes,'' he said.
''Blood was flowing all over. They were not shot. They were beaten up.'' GRAVES DESTROYED Mitja Ferenc, chief historian in charge of grave research, said Yugoslavia's communist authorities persistently refused to acknowledge the executions had taken place and refused to tell relatives where the bodies were buried.
For almost 50 years, people were not allowed to visit the graves. Many of them were destroyed by deliberate explosions or covered by waste. In some places, such as Celje about 60 km (35 miles) east of Ljubljana, parts of towns were built on them.
However, local knowledge persisted: farmers did not allow their livestock to graze in their vicinity. Dezman said only medical students sometimes visited the sites, when they needed skulls or bones for their studies.
''People who come to me are still afraid someone will see them talking to me. They have fear in their bones. They are constantly looking over their shoulder,'' said Dezman.
Although the graves were known to exist, their number was unknown.
''Only after we started researching the first graves did we realise how many secret graves there were, as people started to open up, calling us and telling us of locations they knew of,'' said Ferenc.
In August, Slovenian researchers confirmed there were at least 15,000 victims in a secret mass grave in Tezno, about 120 km (75 miles) northeast of Ljubljana, where mostly Croat and Montenegrin soldiers were executed and buried.
Registrations of secret mass grave locations have grown from 40 in 2002.
''It is high time to acknowledge these graves -- after all, more than 60 years have passed since the Second World War,'' Lado Erzen, the local community's representative for secret graves at Lancovo, told Reuters.
EVIDENCE DESTROYED Slovenians account for about a fifth of all victims but, so far, none of the executioners has been brought to trial.
In 2005, a former Slovenian communist leader, Mitja Ribicic, now 88, was charged with genocide for his role in the killings but charges were dropped because of lack of evidence.
''The evidence is being gathered but the fact is that most evidence has been systematically destroyed in the past,'' Dezman said.
Justin Stanovnik, whose brother Rudolf was among those secretly killed in 1945, said a wider discussion is the only way Slovenians can come to terms with past crimes.
''The genocide that took place has not yet made its way into the public space, it has not been registered yet,'' he said.
REUTERS GT RN1224