Footage has emerged of Russian forces appearing to torture and mutilate several of the men arrested on suspicion of planning the Moscow terrorist attack on Friday evening.
Images and videos posted to social media show a string of brutal punishments inflicted on the terror suspects, with one being forced to eat his own ear, and another receiving electric shocks to his genitals.
One photo appears to show Shamsuddin Fariddun, one of the suspects, pinned to the floor with his trousers pulled down while wires connect an 80-volt battery-powered radio to his genitals.
Another horrifying video shows another man, Saidakrami Murodali Rachabalizoda, having his ear severed - then spitting it out as he is forced to eat it.
Dalerdzhon Mirzoyev, Saidakrami Murodali Rachabalizoda, Shamsidin Fariduni and Muhammadsobir Fayzov appeared in various states of disarray in court
Reuters
More footage shows the terror suspects kneeling and apparently confessing to carrying out the attack.
Following the publication of the videos online, which are thought to have been leaked by Russian security forces, the four suspects appeared at Moscow's Basmanny district court late last night - all in various states of physical damage.
Dalerdzhon Mirzoyev and Rachabalizoda both had black eyes, while the latter's ear was heavily bandaged - which appears to be as a result of the beatings issued by Russian security personnel.
Fariduni's face was swollen, while Muhammadsobir Fayzov - who appeared to be missing an eye - made his court appearance in a wheelchair, falling unconscious as he was brought into the dock.
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The terrorist attack at Moscow's Crocus City Hall killed 137 concert-goers
Reuters
In the early hours of this morning, the court ruled that the fourth suspects in Friday's attack should be put into custody for two months, until May 22, pending a trial.
A court statement on the said Mirzoyev had "admitted his guilt in full", while Rachabalizoda also "admitted guilt".
Russia's state news agency Tass said the men had been identified as Tajikistani citizens.
While seven more people have been arrested in Russia on suspicion of assisting the attack.
Images from the court showed the suspects being dragged into the building by officials
Reuters
The attacks at the Crocus City Hall in the Moscow suburb of Krasnogorsk left 137 dead and almost 200 injured, Russian authorities said.
The violence - which also saw attackers set fire to the venue - came as some 6,000 people enjoyed a rock concert, and followed warnings by the US embassy in Moscow earlier this month for Americans to avoid concert venues and large crowds.
An Islamic State splinter cell, Isis-Khorasan (Isis-K), claimed responsibility for the attacks - but Russian officials refused to acknowledge these claims, instead alleging Ukraine had "prepared a window" for attackers to escape Russia after the attacks.
US national security council spokesperson Adrienne Watson said Isis bore "sole responsibility for this attack" and "there was no Ukrainian involvement whatsoever".