Oleg Nechiporenko, the then Vice Consul for the Soviet Consulate in Mexico City, recalled in his book on Oswald that on September 27th 1963 a man came to ask for a visa to the Soviet Union and:
"Presented his American passport, issued in the name of Lee Harvey Oswald. He also showed a marriage certificate to Marina Prusakova. Nechiporenko told historian Peter Dale Scott that he had not the slightest doubt that the man he met at the Soviet Embassy was Lee Harvey Oswald - or else "his identical twin".
From Nechiporenko's book: "Passport to Assassination", pp 66-67
And this: Patricia Winston, an Australian youg woman who along with her friend were on a bus headed to Mexico City: "It was on the bus to Mexico City that we encountered Lee Oswald. He heard us speaking English and wanted to talk to us, and so we talked about our travels and he told us that he'd been to Russia. He went, then, and got his passport and showed us the Russian stamp on his passport."
From PBS Frontline's "Who Was Lee Harvey Oswald?"
link:
https://www.pbs.org/wgbh/frontline/film/oswald/transcript/And one more: Pamela Mumford accompanied Winston on the bus. She testified that she met and talked to Oswald on the bus headed towards Mexico City.
Here, in part, is her WC testimony:
Miss MUMFORD. I will have to refer to notes. Oh, yes; the first thing he told us was that he was from Fort Worth, in Texas. And he wanted to know where we had been, and we told him we were Australians. He wanted to know the places we had visited. We told him. And he mentioned that he had been in Japan while he was in the Marines, and that was the closest he had got to Australia and that he would very much like to go to Australia.
He then told us that he had been to Russia and asked whether we had ever been to Russia. We said no, and we told him of a friend of ours, a fellow Australian, who had been to Moscow, and her experiences there.
And we asked him what he was doing in Russia and did he have trouble getting in. He said that he was studying there. He had an apartment in Moscow and was studying. We didn't ask him what he was studying.
At this stage he showed us his passport that had a Russian stamp on it; some sort of a Russian stamp. And he didn't mention his Russian wife at all. But We noticed he had a gold wedding ring on his left hand.
source/link:
http://mcadams.posc.mu.edu/russ/testimony/mumford.htm