The former lawyer of Russian opposition leader Alexei Navalny was arrested in Moscow on Tuesday, just a week after he accompanied Navalny’s mother as she appealed to authorities to release her son’s body, Reuters reported, citing Russian media. The detention of Vasily Dubkov was first reported by newspaper Novaya Gazeta Europe and news website SOTA, which cited unnamed sources. It’s unclear what charges Dubkov faces, but other opponents of Vladimir Putin have been detained without explanation or evidence. Dubkov told independent news outlet Verstka on Tuesday that he was promptly released. Meanwhile, the chief investigator who probed multiple alleged crimes by Navalny, Roman Vidyukov, was promoted Tuesday to become the deputy head of Russia’s main investigation department, Novaya Gazeta reported. Tensions have been on the rise in Russia since Navalny mysteriously died at 47 in an arctic penal camp on Feb. 16. Since then, Russian authorities have suppressed any mourning for their longtime foe, going as far as apparently barring funeral agencies and public event halls from hosting a public memorial for Navalny.