Sten Lindstrom is chief of the investigation division of the Swedish National Bureau of Investigation (NBI). In 1987-88, as special prosecutor appointed by the Swedish government to probe alleged wrongdoing on the part of main collaborators in Sweden, Lindstrom personally headed the most wide-ranging probe into the Bofors payoffs. Within a few months of beginning the probe, Lindstrom realised he was not going to get any assistance from the Indian authorities and even some top officials of AB Bofors. Now head of the NBI, he has a deep understanding of all the crucial links in the Bofors story. Lindstrom has scrutinised hundreds of documents and papers and has interviewed all those concerned with the deal. Last month, he created a storm by saying that Sonia Gandhi should tell people all that she knows about Bofors. In a telephonic interview from Stockholm to Ranjit Bhushan, Lindstrom said Sonia cannot claim innocence in the face of findings conducted in the payoffs during the last decade or so. Excerpts: