[sakopov]

> John Melvin said Zailenko was eventually taken to the hospital in Ukiah, and over several days, many different people visited and tried speaking to him in Russian and many other languages, but no one could identify what words exactly he was speaking.

I'm assuming it was Ukrainian? Although if someone tried to speak to him in Russian, they'd be able to understand that he was speaking Ukrainian and naturally understand a good majority of it.

[justsomehnguy]

Petrov/Petroff is a (a very common) surname/lastname in Russian, but never a firstname.

-ko is a suffix denoting a lastname of Ukrainian origin though those were spread around even in Russian Empire.

There are a lot of people with Zayilenko surname in Russia now and Zalenko and Zelenko is still one in Ukraine now.

Given the Wikipedia article on him there is a chance it's just a corruption and he was called Petro Zelenko

[0] Petrov "Petro" Zailenko, a.k.a. Pitro Zalenko

[MikePlacid]

Most probably. Petro is the Ukrainian first name, while Petrov is the Russian last name. Zailenko is the Ukranian last name. So the only valid combination is Ukranian. (Do not ask me how I know this. I can’t explain. Just a trained neural network produces these results).