The 34-year-old Brazilian died after leaving the track and crashing into a concrete wall during the 1994 San Marino Grand Prix.
Frank Williams and two other members of his team, for which Senna drove, are facing manslaughter charges. However, a picture published in the Sunday Times at the weekend, taken seconds before Senna died, shows a small piece of debris lying directly in his path.
Passarini accepted the photograph was admissible evidence. However, he said: "It does not change one iota the prosecutor's conviction that the cause of the Senna accident was the rupturing of his steering column."
Passarini added that "on the basis of enquiries made and on the basis of the conclusions of experts, the prosecution is convinced to have precisely identified the cause" as being a faulty weld on Senna's car's steering column. Williams were maintaining their silence yesterday.
However, the discovery of the photograph, taken by the French photographer Paul-Henri Cabier, makes it less likely Williams and his team will be held responsible for the tragedy.
The small piece of wreckage shown lying in the path of Senna's Williams car just before he spun off is thought to be from an earlier collision involving a Benetton car and a Lotus. A further picture appears to reveal the debris in mid-air after being hit by the Brazilian's car.
The sporting world is awaiting the outcome of the judicial proceedings with considerable interest and concern, as the case is the first to see a constructor having to answer for the death of one of its drivers.Reuse content