For Londoners today, it's just somewhere for a quiet lunch hour.

But for Wladyslaw Czycki and Professor Zdzislaw Stahl, it will soon have a special meaning.

They are Londoners now, but once they were officers in the Polish Army.

In this churchyard will be the only memorial to 15,000 of their comrades,

who died mysteriously in Russia during the war. Some were found buried in

a forest called Katyn. The rest vanished without trace. In this issue,

Echo looks into one of the last unresolved crimes of the last war: The Katyn Massacres.

September, 1939. Hitler invades Poland. The Second World War begins.

While the German armies advanced from the west, the Soviets crossed Poland's eastern frontiers.

Caught in a massive pincer, the Polish Army collapsed and surrendered.

The victors divided the country down the middle and imprisoned every soldier they captured.

Russia took over 200,000. 15,000, half Poland's officer corps, were never seen alive again.

Many were to die near Smolensk in a forest called Katyn.

When they died and who killed them has been one of the great unresolved mysteries of the last war.

In time, the Germans were to accuse the Russians and the Russians were to accuse the Germans.

Whoever did it destroyed half Poland's future leadership.

All we know for certain is that they died like this.

Postcards from relatives in Poland began to be returned undelivered

in the Spring of 1940, a year after their capture. So began the mystery.

A year later, German armies were deep in Russia.

Poland was an ally. Her men were released.

Sikorski, Poland's leader, flew in. His officers were missing. Why?

The Russians were evasive. Sikorski demanded to see Stalin.

Already he knew that until spring 1940, the men had been in three camps:

Kozelsk, Ostashkov, and Starobelsk. Faced with this evidence, Stalin claimed they

had escaped 4,000 miles to Manchuria. Sikorski didn't believe him.

But neither could he believe the men were dead.

Just 400 of the 15,000 were to survive. One was a young cadet officer, Wladyslaw Czycki.

Wladyslaw Czycki: I was an inmate of the camp at Kozelsk. We were there about four

and a half thousand prisoners. I was a cadet officer. In April of 1940,

the Soviet administration of the camp started taking, practically every day, a bunch of officers.

About 70, up to 300 men at a time. And they were taking them out of the camp.

We didn't know anything as to their destination.

The next time they were heard of was not until April, 1943,

when the German Army discovered the mass grave in the Katyn Forest.

Their bodies were lying in the same order as the groups who were leaving our camp.

They were dressed in the same winter uniforms in which we survived the winter of 1939-1940.

Of course, the evidence used later by the Russians tried to indicate that

they were murdered in August or September, but August and September in Russia -

in that part of Russia - the weather is very hot.

Narrator: To the Germans, it was a chance to split the allies.

To Katyn they brought an investigation commission, the press, and even the Polish Red Cross.

The Poles were suspicious. They didn't want to believe the Nazis,

but piece by piece the evidence began to mount up.

Wladyslaw Czycki: The Germans discovered or retrieved from the bodies hundreds of various documents.

First of all, a Russian newspaper. Then letters and correspondence from Poland

to the prisoners of war. And also diaries. Now none of these documents showed any date

which was beyond May 1940. There was a diary kept by a Major Solski, who kept the entries until

the very last moment. In fact, his last entry was: "We are in a forest." And suddenly it dropped.

Narrator: The investigators agree. The men died while Germany and Russia

were still at peace. But now their time had run out.

For the Red Army, the tide of war had changed.

Soon Smolensk and Katyn were theirs again.

The dead were not allowed to rest.

The Russians, refusing an international investigation, appointed their own men.

No Poles were invited.

Their experts, of course, accused the Germans.

The whole grisly process was repeated,

but once more the accused were not there to answer.

New evidence was produced, but world opinion remained confused.

Only 4,000 were found in Katyn. The rest they never accounted for.

Professor Zdzislaw Stahl: In Katyn you had discovered the bodies of the

prisoners of war from the Kozelsk camp only. Over 4,000.

But at the same time, we lost still two camps of prisoners of war.

About nearly 4,000 from Starobelsk, and over 6,000 from Ostashkov.

We had to assume that they were liquidated in the same manner, but in some other places.

Wladyslaw Czycki: In my view, the crime was committed by the Russians.

And all the evidence and facts points to their guilt.

Professor Zdzislaw Stahl: I am also of this opinion, as are the majority of Poles.

The crime of Katyn was committed by the Soviet government.

And I'm sure any impartial international tribunal

would find solid government guilt of this mass murder.

Narrator: Somewhere the killers still live. Their memories are their only punishment.