It is the most complex jigsaw puzzle of all time, so difficult that even a sophisticated new software program will need at least five years to match the millions of pieces.

The German Government has now earmarked €6.3 million (£4 million) for the project: fitting together about 600 million shreds of secret police files ripped up in panic by Stasi agents after the Berlin Wall came down in 1989.

When the puzzle is complete, the files are likely to shed light on some of Germany’s most elusive secrets – on betrayed politicians, on Communist attempts to recruit Nato secretaries and foreign academics, on undercover operations across the globe.

“Even the small samples we have glued together so far have shown that the files deal with important matters,” says Günter Bormann, of the government agency in charge of analysing the Stasi archives.

Until now employees at the agency have been sticking the pieces together by hand, spreading the fragments across large desks and trying to find names, handwriting and signatures that match.

Since 1991, 25 officials have painstakingly processed 350 sacks of paper secrets. Altogether there are 16,250 sacks – at the present rate it would take several centuries to solve the Stasi jigsaw.

The Stasi was ordered by its boss, Erich Mielke, to destroy tens of thousands of files as soon as it became clear that East Germany could not survive as a Communist state. The secret police did not have enough shredding machines, so the agents were told to rip up the paper by hand.

About 45 million A4 sheets were torn into eight or more fragments. The aim was to make a vast bonfire of secrets, but it proved impossible to organise the trucks to take the brown paper sacks to a quarry outside Magdeburg. Instead, the bags were stored in the Stasi cellars and warehouses.

Now a software programme has been devised by the Berlin Fraunhofer Institute of Production Facilities and Construction Technology. The fragments are scanned into a computer and compared for shape, colouring and font size. “You can narrow down the possible matches quite quickly in this way,” Bertram Nickolay, of the institute, said.

The Government has approved the cash needed to process 400 sacks of paper scraps over two years. If that goes well, work can accelerate. “With our programme we should be able to cut the total time needed to five or six years,” Mr Nickolay said. Usually, though, it will need a skilled eye to assess whether the computer has matched the right fragments.

Time is important because the documentation could help Stasi victims to bring compensation claims or seek rehabilitation. Some files could even become evidence in outstanding murder cases.

It has been difficult to secure funding because of opposition from left-wing deputies, some of whom are former members of the East German Communist Party. They have been calculating that if funding is delayed long enough, interest in the Stasi will wane.

The opposite appears to be true. A new Oscar-winning film The Lives of Others – depicting a Stasi officer who develops a conscience while eavesdropping on a suspect couple – has stirred interest in the Cold War days. The former Stasi prison, in Hohenschön-hausen, has become one of Berlin’s principal tourist sites. There are frequent public discussion meetings about the East German past – and many of them are disrupted by heckling Stasi veterans.

Making it fit

— Professional carpet weavers assembled shredded documents seized during the siege of the US Embassy in Iran in 1979

— In 2001 Italian scientists attempting to recreate medieval frescoes destroyed by an earthquake wrote a computer program that placed the hundreds of thousands of fragments with 94 per cent accuracy

— The world’s largest jigsaw puzzle contains 18,240 pieces and, assembled, measures 6ft by 9ft (276cm by 192cm). Dave Cozard took 654 hours to complete it in 2005

Sources: Minnesota Technology Institute; puzzles.about.com ; shrednations.com

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