Police have arrested a man suspected of attacking anti-corruption activist Nikolai Lyaskin, an aide to opposition leader Alexei Navalny, the Interfax news agency reported.

A week after Navalny organized mass protests in dozens of cities throughout Russia, an unidentified man approached Lyaskin in central Moscow on Sept. 15 and struck him over the head with a lead pipe before fleeing.

The Mash Telegram channel published surveillance footage this week of the attack.