FSB officers may have been in the concert hall during the terrorist attack in Moscow, according to speculation posted on the Nexta Telegram channel.

“We analysed the footage of the terrorist attack at Crocus City Hall and found that in the concert hall where the bloodiest events of the terrorist attack took place, there are several people dressed similarly, wearing blue sweatshirts and jeans,” a post by Anna Lena said that includes pictures from the concert hall just before the shooting began.

While no concreate evidence has been presented, Russian social media is buzzing with conspiracy theories, linking the FSB security services to the attack on March 22 that killed more than 140 innocent victims.

Several observers have pointed out that there are at least four men wearing identical blue sweatshirts and jeans in the concert hall. Studying the video from those first moments after shots were fired the men appear to remain calm while the rest of the crowd panicked.

“First of all, their clothes. The blue sweatshirt and jeans are a pretty casual combination that helps them blend in with the crowd while being highly visible to each other. They are clearly visible at the exit, but if you look closely you can spot the “men in blue” in other parts of the hall,” according to Lena.

“Second, their behaviour. They are all calm, not running anywhere and not panicking. In the video, a man in a blue sweatshirt and jeans even pushes a woman who was heading for the exit back into the aisle between the seats. Later, this man starts filming with his phone. You can see that the “Men in Blue” look at each other from time to time,” says Lena.

At some point in the video, a male voice from behind where the alleged "FSB officer" is sitting suggests closing the doors, and the "men in blue" take turns supporting this idea, creating the illusion of mass support for this idea. As a result, many people are unable to leave the hall because the doors are closed and die.

In day following the tragedy many people have raised questions about the official response and suggested that the FSB had a role the attack with the intension to use what has been the biggest terrorist attack on Moscow in two decades as an excuse to further tighten repression. The attack is also a way to prepare the population for a new mass mobilisation to raise fresh troops for the war in Ukraine.

Critics say that the attack was a massive security failure by the FSB that appears to have been caught completely off guard. Questions have been raised at the authorities’ slow response. The Russian Guard’s rapid response team took over an hour to arrive at the scene after the alarm was raised. Moreover, Russia’s OMON riot police have a building in the same district only 10 minutes’ drive away from the Crocus City mall but also failed to respond to the alarm.

The FSB has been accused several times of being complicit in terror acts that have been subsequently politically useful to the Putin regime. The most famous was a series of apartment bombings in 1999 ahead of the elections in 2000 that installed Vladimir Putin as president. Blamed on Chechen terrorists, a series of bombs destroyed apartment blocks in Moscow killing hundreds in their sleep. Evidence later emerged that the FSB may have been behind the bombings, which Putin used to justify scaling up Russia’s military presence in the second Chechen war.

Likewise, following the Dubrovka terrorist attack in 2002, where a group of militant Chechen terrorists took hundreds of hostages in the Nord Ost theatre siege, it was suggested that the FSB had also played a role.

Famous Russian opposition journalist Anna Politkovskaya told state TV host Vladimir Solovyev that she had sources that claimed the terrorist attack on the Dubrovka theatre was organised by Russian secret services. Politkovskaya was later shot and killed in cold blood outside her apartment on Putin’s birthday.