Swiss prosecutors generally refuse to override the secrecy laws to help foreign authorities prosecute so minor an offense.
It is clear that the daughters are under investigation in Switzerland and Russia based on questioning this week by Swiss prosecutors.
Swiss prosecutors value the artwork taken from Switzerland alone at $1.2 million.
But the stance of the Swiss prosecutor and the police is to ignore any evidence that contradicts their theory.
In the end the Swiss prosecutors were not able to ask Mr. Salinas any of their questions.
Swiss and German prosecutors opened a criminal investigation.
Swiss and French prosecutors believe that Mr. Guelfi received more than $4 million for his services.
Last year, Swiss prosecutors told reporters they couldn't prosecute Zardari since he had immunity.
Swiss prosecutors declined to comment on the letter or on the case in general.
He told Swiss prosecutors that he had served as a financial adviser to the President's brother.