Both the geography of the plot and the timing of its disclosure are fueling questions.
A spokeswoman for Ukraine's security agency, the SBU, said the arrests were made following an explosion at an apartment in the city center in the Black Sea port of Odesa that killed an accomplice.
Local journalist Oleksandr Galyas counters that the plotters are highly unlikely to have set up headquarters in the heart of Odesa's historical center a stone's throw from the city's police head office.
"The old courtyards of Odesa are a closed space surrounded by gates, where people know each other and know roughly what their neighbors do. It's impossible to live unnoticed in such a courtyard," Galyas says. "This raises the question of why all this happened precisely in Odesa, in the very city center, in the old courtyards?"
Moreover, the official story behind the Odesa explosion in January that allegedly uncovered the plot has already changed twice.
The Ukrainian media first ran reports quoting officials saying the plotters had targeted a prominent Odesa businessman. Later, reports claimed that pictures of various popular public places in Odesa had been found on a computer seized from the suspects, suggesting plans to attack a densely populated spot in the city.
The February 27 report on Russia's Channel 1 also glossed over the arrest of Osmayev's father, which was widely reported by the Ukrainian press.
"First the attack targets an oligarch, then public spaces, now they are saying that in the end no bombing attack was being plotted in Odesa and that the attack was in fact to be carried out in Moscow," Galyas says. "This whole story is very strange."
Andrei Soldatov, a Russian intelligence expert, agrees.
Additionally, specific details about how the suspects intended to murder Putin, he says, are suspiciously scarce.
"If you formally announce a foiled assassination attempt, then you must provide details -- how this attempt was planned, how it was planned and when it was due to take place," Soldatov says. "In my opinion, the testimonies of the detained suspects clearly show that they were indeed planning some kind of attack but that the attack on Putin was scheduled to take place at a much later date."
The identity of the main plotter has also fueled doubts.
Channel 1 ran footage of Adam Osmayev, an ethnic Chechen, confessing to the plot on behalf of the Caucasus Emirate -- a group led by Chechen warlord Doku Umarov that has claimed responsibility for a string of deadly attacks in Russia.
Osmayev, however, comes from a prominent family known for its close ties with Ramzan Kadyrov, Chechyna's Kremlin-appointed strongman leader and a close Putin ally.
Adam Osmayev's uncle, Amin Osmayev, even served as a deputy in the Federation Council, the upper house of Russia's parliament in late 1990s.
Repeated calls by RFE/RL to Amin Osmayev went unanswered.
Musa Muradov, a Chechen correspondent for the Russian daily "Kommersant" daily who was able to reach Amin Osmayev on February 27, said the former senator strongly denied any links between his nephew and Chechen rebels.
"He said the Osmayevs had always been loyal to Russian authorities and that many of them had held high-ranking government jobs. Some of them still hold influential positions," Muradov said. "The Osmayev family is well-known in Chechnya. Concerning Adam, his uncle said he could have become involved with some criminal gang due either to unawareness or a misunderstanding. The family is still trying to find out what happened and that's why they don't want to comment yet."
Amin Osmayev said his brother Aslanbek -- Adam Osmayev's father -- who had traveled to Odesa after hearing of his son's arrest, was released February 27.
Channel 1 described Osmayev prior to his alleged involvement with militants as a "respectable young man" who studied economics at the University of Buckingham in Britain. According to the report, it is in London that Osmayev later got acquainted with militants from Russia and learned to assemble explosive devices.