A Swiss prosecutor seeking to try a former Kremlin aide, Pavel Borodin, for money laundering says he has evidence that Borodin had access to Swiss bank accounts containing around $25 million (SFr41.75 million), and that the money has now disappeared.
Bernard Bertossa told Monday's Neue Zürcher Zeitung newspaper that he would pursue Borodin until the former Kremlin property manager explained where the money had gone.
Bertossa said he was waiting "for evidence that the money has been legally deposited in accounts in Russia".
He suspects that Borodin received the $25 million from two Swiss-based firms - Mabetex and Mercata - in return for granting lucrative contracts to renovate the Kremlin.
The former Kremlin official is being held in custody in New York where he is waiting extradition to Switzerland. He was arrested last month on a Swiss warrant, when he arrived in the United for President Bush's inauguration.
Bertossa also made clear he was not prepared to consider a Russian request to withdraw the extradition order and allow Borodin to come to Switzerland of his own accord.
"[The Russians] have said they are ready to send Borodin. But I have been given no guarantees. In any case, in these matters guarantees don't exist."
Bertossa said, too, that he was sceptical about Russia's decision to drop its investigation against Borodin. Russian prosecutors withdrew their charges in December, citing lack of evidence.
"Yesterday the Russians were saying that this affair involved criminal activities, today they are saying it doesn't."
Moscow has been putting pressure on the Swiss government to intervene in the Borodin case. On a recent visit to Bern, the Russian foreign minister, Igor Ivanov, asked his Swiss counterpart, Joseph Deiss, to do what he could to resolve the matter as soon as possible.
Deiss said he could not intervene because the case was "a legal matter and not a political affair". Bertossa confirmed he had not been in contact with Deiss's department about the case.
He added that legal cooperation with Russia "functioned less well than with many other countries".