St. Petersburg police have detained a prominent philosophy professor for allegedly donating 3,500 rubles ($42) to groups affiliated with the late opposition activist Alexei Navalny.

St. Petersburg police said it cooperated with the Federal Security Service (FSB) to detain a 58-year-old local resident as part of a criminal case into financing extremist activity that was opened on July 31.

While the police withheld his name, several media outlets identified the man as Igor Zaytsev, 58, an associate professor and deputy dean of the faculty of philosophy and theology at the Dostoevsky Russian Christian Humanities Academy.

In a video released by the police, law enforcement officers were heard asking Zaytsev about his electronic devices before carrying out extensive searches in his home.

“I personally supported Alexei Navalny,” Zaytsev told the officers on camera.