The agents from Russia's Federal Security Service (FSB) wanted to know who put 85-year-old Nikolai Suvorov up to it. After all, pensioners in the provinces of southern Russia don't decide all by themselves to file lawsuits naming President Vladimir Putin an "enemy of the people" and calling for his removal from office.
Or do they?
"They thought the Communist Party made me write the complaint," Suvorov told RFE/RL's Russia Service by telephone from his home in the town of Balakovo in Saratov Oblast. "The Communist Party doesn't have anything to do with this. I always voted Communist. The Communist Party is the only party for the people, while the rest are for the rich. But I wrote my complaint myself by hand, and the lawyers then typed it up."
"They don't type my things up anymore -- they are all afraid," Suvorov added.
Suvorov made headlines earlier this month when he filed his suit against Putin. Saratov appellate court Judge Tatyana Leskina caused an even bigger scandal by accepting the case and setting a date for a preliminary hearing.
But just days later, the court reversed itself, deciding that Putin had constitutional immunity from prosecution. The case was quashed, and Leskina resigned "of her own accord."
[The FSB agents] were polite. They didn't try to frighten me. They just wanted to know who put me up to it."
"They told me that she left on her own," Suvorov said. "But they are lying to me. I think the judge was fired. She paid the price for letting the case go forward."
And that's when the police and the FSB showed up to question Suvorov.
"They were polite," he said. "They didn't try to frighten me. They just wanted to know who put me up to it."
Suvorov, who said he intends to continue trying to push his lawsuit, is certainly an unlikely revolutionary.
"I don't know what the Internet is," he said. "All I have is television." He said he doesn't even have a radio, and he doesn't listen to relatively liberal stations like Ekho Moskvy or RFE/RL's Russian Service.
"All the information in my complaint I took from the television," he said. "But I don't just watch television. I also look around and see how the people are living. After the war, people were building, repairing things, lifting themselves up. But now the country doesn't need anyone."
Suvorov was quick to restate his indictment of Putin.
"Putin is an enemy of the people," he said. "There are 17 points in my complaint. The main one is that he has impoverished the people. Every year, he sends $2 trillion to other countries, and nothing remains for the people. Pensions are a joke, and most of that money goes to housing costs. Utilities are now terribly expensive. Some prices in stores have quadrupled in the last two years."
Suvorov, however, praised Putin for his annexation of the Ukrainian region of Crimea and for supporting separatists in Ukraine's Donbas.
His friends and relatives -- who are also mostly Communist supporters, although some support Vladimir Zhirinovsky's nationalist Liberal Democratic Party of Russia -- unanimously supported his case against Putin, Suvorov said.
The experience with the ill-fated lawsuit has added one more point to Suvorov's indictment.
"Our judges are not independent and Putin can never be held to account," he said. "What do we need such a president for?"
RFE/RL correspondent Robert Coalson contributed to this report