Russia said on Monday it had arrested a woman suspected of blowing up a prominent war blogger in a St Petersburg cafe the previous day as nationalist politicians and commentators accused Ukraine of the crime and called for retribution.

Maxim Fomin, a well-known Russian military blogger and cheerleader for Russia’s invasion of Ukraine who called himself Vladlen Tatarsky, was killed on Sunday in what appeared to be the second assassination on Russian soil of a figure closely associated with the conflict.

The woman arrested — Darya Trepova — was a Russian citizen who had previously been detained for protesting against the war in Ukraine, the state news agency TASS said.

With over 500,000 followers on the Telegram messaging service that is popular in Russia, Tatarsky — who had himself fought in Ukraine in the past — mixed ultra-nationalist messaging with criticism of the way Russia is prosecuting what it calls its “special military operation” in Ukraine.

More than 30 people were injured in the blast which killed him. Some Russian commentators saw the bombing as the latest sign that violence related to the war in Ukraine is increasingly spilling onto Russian territory.

Russian investigators said they had arrested Trepova, a 26-year-old, who they said was suspected of bringing the explosives into the St Petersburg cafe.

TASS suggested Trepova may have approached Tatarsky at Sunday’s cafe event and given him a statue as a gift which was packed with the explosives that killed him.

Unconfirmed Russian media reports said she had been discovered hiding in the St Petersburg apartment of a friend of her husband’s and had planned to flee to Uzbekistan.

Reuters could not immediately confirm those details.

Trepova had appeared on an interior ministry wanted list earlier on Monday.

Court records cited by TASS showed she was detained on Feb 24 of last year, the day Russia invaded Ukraine, for taking part in what the authorities deemed an illegal anti-war protest.

Russian politicians, without evidence, on Sunday evening immediately pointed the finger of blame for Tatarsky’s killing at Ukraine’s intelligence services. Ukraine did not claim responsibility for the killing — a Ukrainian presidential adviser blamed “domestic terrorism” instead.

Darya Dugina, the daughter of a prominent Russian nationalist ideologue, was killed in a car bomb attack outside Moscow last summer that Russia blamed on Kyiv. Ukraine denied involvement.

Russia’s FSB security service said last month that it had thwarted a Ukraine-backed car bomb attack on a prominent nationalist businessman who has been a cheerleader for Moscow’s war in Ukraine.

Margarita Simonyan, editor-in-chief of state media outlet RT, welcomed Trepova’s arrest on Monday, saying her detention had avoided what she called “a national disgrace”.

Simonyan, like other hawkish commentators, made it clear on Telegram that she wanted Russia to hit back hard against whoever had killed Tatarsky. “Well well. Are we going to forget and forgive this?” she asked sarcastically.