Russia’s FSB is facing mounting criticism over its claim that a Ukrainian woman assassinated the daughter of a prominent Putin ally, with critics insisting it should look inside its own borders first.

Speculation is now rife that the real architects of last Saturday’s car bombing are either the security services themselves – the victim, Darya Dugina, and her father Alexander had been criticising how long the war was taking in the Ukraine – or a new anti-Vladimir Putin group which has been formed in Russia called the National Republican Army (NRA).

The FSB boldly announced it had solved the murder within 48 hours, saying on Monday that Ukrainian secret services had organised the hit. It released still photographs of the assassin – Natalya Vovk – apparently staying at the same apartment block as Miss Dugina, then crossing the border in a Mini Cooper car into Estonia on Sunday after the hit.

Its explanation, however, drew instant mockery even before the Ukrainians, and later the Estonians, rubbished the FSB theory. Critics pointed to the image of a baby in the back of the car, saying assassins didn’t drive around with their children, while pointing out that there was a whole catalogue of murders in Russia which the FSB has failed to solve going back decades.

Former Russian state deputy Ilya Ponomarev instead pointed to the NRA as the source of the attack, saying that both Alexander Dugina, an ally of the Russian president sometimes referred to as “Putin’s brain,” had been the targets. Earlier theories had been that Ms Dugin was only killed because she was driving her father’s car after he changed his mind about travelling home with her.

The NRA, in a statement on the Telegram channel Rospartizan, ridiculed the FSB’s findings, claiming that Russian authorities are “so afraid of the partisans that they are ready for any fables in order to maintain the appearance of total control.”

“So, according to the FSB, the Ukrainian woman is to blame for everything,” the group wrote, highlighting the security service’s numerous findings, including that the Ukrainian citizen arrived in Russia in July with her daughter, rented an apartment in the same building as Dugina, spied on Dugina, and left the country using Ukrainian license plates.

“All this became known a day after the murder—this is the speed of the investigation!” the NRA wrote.

The NRA suggested that the Ukrainian woman who the FSB said entered Russia with her daughter and left for Estonia is most likely a refugee from the occupied Mariupol region. The hard-hit Ukrainian port city was seized by Putin’s troops in the early stages of the war, which began on February 24.

“There are thousands of such women fleeing the occupied city to Europe through Russia. Playing this story is very convenient for Putin’s special services—they found the ‘guilty’ and have nothing to show,” the NRA continued.

Ponomarev said the NRA authorized him to issue their “manifesto” via his Rospartizan Telegram channel.

The group apparently consists of Russian activists, military members, politicians who are “now fighters and partisans,” and said it opposes the war launched by Russia against neighbouring Ukraine.

The NRA has yet to comment on whether it carried out the assassination. Ukraine, meantime, claimed it is part of a false flag operation by the Russian state security services in order to incite “public mobilisation” against Ukraine.

Oleksiy Danilov, Secretary of Ukraine’s National Security and Defence Council, later told reporters: “We have nothing to do with undermining this lady – this is the work of Russian special services.”

Estonia said the claim that an assassin had fled across into its territory was another provocation, on top of many provocations over the years.”