Now, NTV, which is owned by the state-controlled energy giant Gazprom, has explained the contradiction: the international man of mystery suffers from schizophrenia.
In a dramatic segment that aired on April 13, NTV claimed that the channel had "inadvertently become hostage to a grand hoax" and accused the Western media of exploiting a mentally ill man to discredit Russian journalists.
The revelation about Petkov's alleged mental state followed a YouTube video that went viral last week comparing separate interviews he gave to NTV and Rossia 1 television from what appears to be the same hospital bed.
WATCH: NTV's Follow-UP Report On Andrei Petkov
In one interview, he tells NTV that he is a German mercenary who ferried in 500,000 euros for the Maidan protesters but was beaten up during a melee sparked by Ukrainian ultranationalists in the southern Ukrainian city of Mykolaiv.
Rossia 1 says he is a pro-Russian protester assaulted by "radicals" bussed in by the Ukrainian government.
The YouTube video of the two Petkovs has racked up more than 450,000 views and was picked up widely by Russian bloggers, who gleefully mocked what they called crude state propaganda.
WATCH: The Two Petkovs
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But in the April 13 follow-up report, NTV interviewed a man who claimed to be Petkov's brother, and said his brother has schizophrenia.
"He has this every spring," he said. "The man is not bad, good or evil. He is simply mentally ill."
Petkov's mother died in the 1980s, and he took the loss hard, NTV reported. He also never worked or traveled abroad as he claimed in his first interview with the channel, NTV said.
But Petkov was close to the protests in Mykolaiv and was injured, NTV said, adding that he woke up and imagined himself as a German millionaire. He even learned German from old records, according to the report.
NTV caught up with Petkov for a follow-up interview from the same hospital bed. He did not deny fabricating his story.
"But you must understand that I have a concussion, I have a disability, I have a gunshot wound to the head, I have a concussion, I do not sleep," he said. "I do not sleep, I cannot sleep for weeks, and when I cannot sleep, I start to get weird."