Ambiguity has trailed the Russian hacking story all along. Mr. Fomenko, in an interview in a bar here called Rocks, flatly denied having any ties to the hacking. Yet he sports a collarbone-to-jaw tattoo of what he described as a version of the theatrical mask that is the symbol of the hacking group Anonymous.

He denied any connection to the group, saying he simply liked the symbolism of the mask. “A person can be evil, or a person can be good, or a person can hide who they are,” he said.

The equivocation of responses by Mr. Putin and Mr. Fomenko is studied and deliberate, Kenneth Geers, a senior research scientist at Comodo, a cybersecurity firm, and a former cybersecurity officer with NATO, said in a telephone interview.

“You are not saying yes, you are not saying no, so it’s frustrating for the victim, and it’s intimidating,” he said. “You are suggesting there is more to come.”

The tattoo, though, “is something of a giveaway.”

Mr. Fomenko, raised by a single mother, studied computer science at a technical college. He said he founded King Servers in 2008 when he was 18, buying computer servers and arranging for their installation remotely in Fremont, a city he said he had never visited.

He said he had about a thousand clients, 20 percent to 30 percent of whom are pornographers. Authorities in the Netherlands, he said, have notified him on several occasions that his servers had been used for spreading malware, advertising counterfeit designer handbags and distributing child pornography; in those cases, he said, he immediately revoked the rental agreements and closed the servers.

“If the person looks young, maybe 17 or 18, you cannot tell, we shut them down,” he said. “Every company has their problems. You cannot control everything.”