In the wake of the bombing death of Russian military blogger Vladlen Tatarsky in a St Petersburg cafe, Russian authorities have sought to implicate both Ukraine and the domestic opposition.
However, experts are sceptical of Moscow's narrative and say there are others with potential motives — including factions within the Russian establishment.
Russian investigators on Tuesday charged Darya Trepova, a 26-year-old woman, with terrorism offences in relation to the incident on Sunday.
They allege Ukrainian intelligence organised the killing with help from supporters of jailed Kremlin critic Alexei Navalny.
A video posted to messaging app Telegram shows a woman the police say is Trepova, walking into the cafe carrying a box containing the bomb inside a bust of Tatarsky.
Court records show a woman with the same name previously received a 10-day jail sentence for participating in a protest over Russia's invasion of Ukraine.
Trepova also once registered for an anti-Kremlin tactical voting scheme promoted by Navalny's movement.
However, Trepova's husband said she had been framed and did not know about the explosives.
Russian foreign and security policy expert Matthew Sussex says the only thing we know for certain so far is who the Russian government wants to believe is responsible.
Dr Sussex said it was possible that a domestic anti-war group was behind the bombing.
"It's possible, but if so, that's a big step up in sophistication," he said.
"[Anti-war groups] have tended not to be particularly well developed in operations that they've done, mainly just firebombing recruitment centres.
"A lot of that has gone on but it hasn't in most cases caused too much damage, just destroyed files or things like that.
"It's certainly the case that the Russian government would be keen to go after those who it sees as being hostile to the war, someone with links to peace movements in Russia would probably give you a fairly good indication of who the regime wants to target, regardless of who might be responsible."
Meanwhile, Alexey Muraviev, an associate professor of National Security and Strategic Studies at Curtin University, said Russia had a clear strategic motivation to classify the bombing as an act of terrorism and link it to Ukrainian forces.
"If this is classified as a political act and Zelenskyy is classified as a terrorist, then it gives the Kremlin the opportunity to reject peace talks," Dr Muraviev said.
"Putin can turn around and say: we don't negotiate with terrorists."
A Ukrainian target?
Interest in Tatarsky, whose real name is Maksim Fonin, has focused on his role as a military blogger who was openly critical of the Russian army and repeatedly called for an escalation of force in Ukraine.
But his notoriety in Ukraine goes much farther back. Originally from eastern Ukraine, Tatarsky joined Russian proxy forces in 2014 when they first occupied the city of Donetsk.
After stepping down as a military officer, he began reporting from the frontline to an audience of more than half-a-million followers on Telegram and obtained Russian citizenship in 2021.
"We will defeat everyone, we will kill everyone, we will rob everyone as necessary. Just as we like it," Tatarsky said in a video posted to his account last year.
But was this enough to make him a target of Ukrainian forces?
Dr Sussex, who is a fellow at the Australian National University's Strategic and Defence Studies Centre, said Tatarsky had a large-enough profile to be considered a worthwhile target for Ukraine.
"He was a fairly prominent blogger and from memory was on stage with Putin to receive the handover of Donbas, so he was an important figure," he said.
But according to Dr Muraviev, the biggest indication that Ukraine wasn't involved is the simple fact that they haven't said so.
"A bombing in St Petersburg, Vladimir Putin's hometown, means a great failure of the Kremlin," he said.
"[Ukraine] would take full credit."
Fighting factions?
Parallels can be drawn between the deaths of Vladlen Tatarsky and Darya Dugina, the daughter of an ultranationalist Putin supporter who was killed in a car bombing last year.
Both Tatarsky and Dugina were killed by improvised explosive devices allegedly delivered by women and both were vocally critical of the military strategy in Ukraine.
While Putin has effectively silenced opposition from within Russia, there has been growing discontent between factions who are supportive of the war in Ukraine, most publicly between the Russian Defence Minister Sergei Shoigu and the head of Russia's notorious Wagner mercenary group, Yevgeny Prigozhin.
Former Australian ambassador to Russia Peter Tesch said these rivalries were commonplace within Russia and had contributed to Putin's consolidation of power.
"This is a very personalised system of power where institutions of the state are actually quite weak," Mr Tesch said.
Taking into account Prigozhin's links with Tatarsky suggested the bombing could be evidence of these rivalries turning deadly.
"Prigozhin has pissed off quite enough people in the [Russian] intelligence community, and certainly in the armed forces, that a figure who is associated prominently with him could well become a legitimate target.
"We can only speculate about why [he was] so vocal; he clearly wanted to be noticed, he clearly wanted to create a role and a place for himself and his private army."
Putin has increasingly used mercenary fighters in Ukraine, most recently in Russia's attempts to capture the eastern Ukrainian city of Bakhmut.
Prigozhin, who used to own the St Petersburg cafe that was targeted, raised the Russian flag in Bakhmut to honour Tatarsky after his death.
In a cryptic social media post, he also challenged the Kremlin narrative that Ukrainian authorities were behind the bombing.
"Tatarsky was respected by Wagner people," Dr Muraviev said.
"Prigozhin was actually challenging the official views of the Kremlin, suggesting that the perpetrators may actually be [from] elsewhere but Ukraine."
Can we ever be certain?
Amid extreme scepticism in the West about the independence of Russia's judiciary, it may never be known who was really behind the bombing in St Petersburg or other attacks.
Russia has now charged Darya Trepova as a terrorist, which Dr Muraviev believes will give the Kremlin an "opportunity to cleanse the last of the opposition in the country" and reject peace talks with Ukraine.
Meanwhile, the aggravation of rivalries and resentments among Russian elites plays to Ukraine's broader strategic agenda, according to Peter Tesch.
"They are certainly not strategic losers out of this, except for the fact that the Kremlin will spin this evermore to support the justification for ever-more brutal assaults on Ukraine and its civilian population and infrastructure, despite the Kremlin's lies about not targeting these."
ABC/wires
