Mr Krawczyk worked for the District Prosecutor's Office in Katowice. He was the first, in 2005, to investigate ties between Barbara Kmiecik, the coal industry's grey eminence, and Barbara Blida, then SLD deputy, and other politicians of the postcommunist left.
Mr Krawczyk failed to come up with conclusive evidence that they had taken bribes. So the only charges pressed were against Kmiecik for obtaining undue government subsidies. That was in January 2006, shortly after the PiS had won the general election.
It was too little for a case that had been touted as the 'coal mafia'. Three months later, the higher level is activated - the Regional Prosecutor's Office in Katowice. It launches its own inquiry into the alleged corruption of SLD politicians and chief executives of coal companies. The Katowice office is a protégé of the new justice minister, the radical young Zbigniew Ziobro. It handles all the cases, from all over the country, that are important to the ruling PiS. The office is headed by Krzysztof Sierak, Mr Krawczyk's former head at the district office.
Mr Sierak appoints a special team to run the inquiry. The group bases on evidence gathered by Mr Krawczyk. Its task is to prove what Mr Krawczyk had failed to prove - that Ms Kmiecik had corrupted Ms Blida and other SLD politicians. In April 2007, Internal Security Agency officers knock at Ms Blida's door with an arrest warrant.
Ms Blida commits suicide.
In July 2008, Mr Sierak testified before the parliamentary committee of inquiry investigating the tragedy. He said firmly that at the time when he worked for the district office, he had no interest in the case whatsoever.
Mr Krawczyk, who testified later, called that a lie. He testified that in November 2005 Mr Sierak read the case files and signed documents. He said of Mr Sierak's role, 'He suggested that I take a look again at the Blida case. I said I wasn't interested in politics and that I wouldn't participate in the campaign against the leftwing that the Kaczyński brothers and Mr Ziobro had pledged'.
The parliamentary committee of inquiry ordered a confrontation. Then Mr Sierak admitted he may have been familiar with the Blida case files and may have signed documents, but he denied ever insisting that charges be pressed against her.
These contradictions caused Warsaw prosecutors to open an inquiry to ascertain whether Mr Sierak had given false testimony.
Mr Krawczyk testified at end-April. He was shown a decision, dated 3 March 2006, officially opening an inquiry into Ms Blida and the 'coal mafia', and the document's handwritten working version (to be clean typed). Both documents feature Mr Krawczyk's name and bear his signature. According to Gazeta's sources, Mr Krawczyk testified that he was not the author of these documents.
He also said the documents were forged.
He added that the working version was not written in his handwriting.
Citing confidentiality of the pending inquiry, Mr Krawczyk refuses to talk to Gazeta.
Mariusz Martyniuk, spokesperson for the Warsaw prosecutor's office, confirms Mr Krawczyk has been questioned.
'We shall investigate all new circumstances', says Mr Martyniuk, but he refuses to go into any detail on the inquiry's planned direction.
Prosecutor Agnieszka Wichary from the Regional Prosecutor's Office in Katowice says only that 'No one has informed us that the validity of the Blida inquiry opening decision has been called into question'.
Why did Mr Krawczyk not tell the parliamentary committee of inquiry about the forgery? Because he was not shown then the controversial document. No one suspected at the time it may have been doctored.
'If the graphologists confirm the forgery, the key question will be who did it and why', says Marek Wójcik, PO deputy and member of the committee of inquiry. 'It would be proof that the prosecutors opened the inquiry into the coal mafia with ill intensions - of discrediting the leftwing'.
Mr Ziobro did not return Gazeta's phone calls.
His then deputy, Jerzy Engelking, says that forging the inquiry opening decision would not make sense.
'After all, such a decision can be signed by anyone, even a simple assistant prosecutor. It was not a key decision', says Mr Engelking. But he adds that the issue needs to be explained.
'Perhaps it was an attempt to discredit Mr Krawczyk?', he wonders. 'If the case against the SLD collapsed, he would have been made the scapegoat'.
Translated by Marcin Wawrzyńczak