Russian investigators on Tuesday charged Darya Trepova with terrorism over a bombing attack in St. Petersburg that killed a prominent military blogger and wounded dozens of people.
Trepova, a 26-year-old woman, was detained after an explosion ripped through a cafe in Russia's second city at the weekend, killing Vladlen Tatarsky, a high-profile blogger and supporter of Moscow's assault on Ukraine.
The Investigative Committee, which probes major crimes, said Trepova acted on orders from "figures based in Ukraine" and committed a "terror attack by an organized group."
The statement said that Trepova had brought a statuette rigged with explosives to a cafe located along the Neva River not far from the historic city center and handed it over to the blogger, whose real name was Maxim Fomin.
On Monday, the Investigative Committee and the National Anti-Terrorism Committee both claimed that supporters of jailed Kremlin critic Alexei Navalny helped Ukraine carry out the attack on the military blogger, who had more than half a million followers on social media.
Political observers said the bombing attack could be used to justify a further crackdown on critics of Moscow's offensive in Ukraine.
In a chilling post on messaging app Telegram, former President Dmitry Medvedev on Tuesday accused the country's embattled opposition of "waging a war" against ordinary Russians and "executing their compatriots."
"Terrorists" should be "exterminated like rabid dogs," added Medvedev, who is now deputy chairman of Russia's security council.
Ukraine has blamed Russian regime opponents for the blast.
In a video released by his spokespeople, the head of the Wagner paramilitary group, Yevgeny Prigozhin, said he arrived in St. Petersburg from the frontline hotspot of Bakhmut in eastern Ukraine to "honor" the memory of Tatarsky.
"Vladlen Tatarsky tried to consolidate society to fight the external enemy," said Prigozhin at the cafe's bombed-out premises, referring to Ukraine and NATO.
He blamed top city officials including the governor for not appearing at the scene and being unable to mobilize young people for the fight against "evil."
Prigozhin also met with members of an ultra-nationalist group dubbed Cyber Front Z, pledging support. Prigozhin says he used to own the cafe but handed it over to Cyber Front Z.