By Jon Silverman in Riga

In a forest just outside Latvia's capital, Riga, a massive slaughter took place in the winter of 1941.

At Rumbula, 30,000 Jews were herded to their deaths in freezing temperatures.

Archive pictures show the victims' last moments, as they were escorted to the killing pits by the local security police, the Arajs Kommando.

Now the BBC has learned that some of the murderers have been quietly rehabilitated, given extra pensions and welfare benefits.

The information has been obtained by the Simon Wiesenthal Centre, which tracks suspected Nazis. The documents tell a revealing story.

The centre's Efraim Zuroff says: " We can give you the dates when they got the rehabilitation. Some people applied several times and only got it recently.

"But the evidence is absolutely unequivocal, it's clear-cut. We have over 40 names of people convicted of terrible crimes who, during the past few years, were granted rehabilitation by the Latvian authorities."

Archives

The evidence was found in the Latvian state archives, where thousands of files were opened by the former Soviet secret police, the KGB, over a period of decades.

We were not allowed to see the file on Konrad Kalejs, the former commando officer who left the UK and returned to Australia in a blaze of publicity earlier in January.

But state prosecutor Janis Osis, who is in charge of the Kalejs case, says it is too easy to generalise about war criminals.

"The Arajs Kommando didn't only consist of executioners but also soldiers who fought against Soviet Red Army partisans. They didn't commit any war crimes," says Mr Osis.

Terrible things

But the evidence in the Jewish Documentation Museum paints a different picture.

It is a matter of historical record that the group's leader, Viktors Arajs, was jailed for war crimes in the 1970s.

Arnis Upmolis was also convicted of war crimes and spent 10 years in Soviet labour camps.

He joined the Arajs Kommando voluntarily in 1942.

"I was one of the guards when the Jews were shot," says Mr Upmolis. "My job was just to stop trespassers."

But although he says he was not directly involved, he admits that terrible things were done. "There was a special execution unit, and yes, it was a crime against humanity."

Respects

A bleak stretch of land outside Riga is the site of a former concentration camp, where inmates died of cold, of hunger, and random killings by the guards.

Those guards were part of the Arajs Kommando.

Now, with rehabilitation, it seems they are no longer counted as criminals.

Jewish survivors come here to pay their respects, but their number dwindles by the year.

The survivors say that if education about the Holocaust dies with them, their suffering will have been in vain.