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.
Lyaskin was taken to a hospital and diagnosed with skull injuries.
An "informed source" told Interfax that police have detained a 36-year-old Moscow resident with a criminal record who has also been under psychiatric observation.
Moscow police headquarters confirmed to Interfax that the man who had attacked Lyaskin had been brought to a police precinct but declined to provide his name.