A mysterious academic who allegedly acted as a link between Donald Trump's presidential campaign and the Kremlin is "missing and may be dead", according to court papers.
Joseph Mifsud, 57, became embroiled in scandal after he was said to have offered "dirt" about the Democratic candidate Hillary Clinton to a Republican aide at a London hotel.
The Maltese professor, based at the University of Stirling in Scotland until last year, has previously denied suggestions that he was a Russian agent saying: "Secret agent!
The documents said all the defendants in the case have been served with the complaint, "with the exception of Mifsud (who is missing and may be deceased)".
He is the first former campaign aide to be sentenced in special counsel Robert Mueller's Russia probe, which is also investigating any possible collusion between the Trump campaign and Moscow.
Authorities were alerted after Papadopoulos told an Australian diplomat during a drinking session in a London pub about his meetings with Mifsud.
He was once described as 'Ambassador Mifsud' but although he worked for six months in the private office of the Maltese foreign minister, he was never a diplomat. »