The Russian authorities on Thursday arrested a suspect who acted as an accomplice in the attack by gunmen on a suburban Moscow concert hall that killed over 140 people.
Russian Health Minister Mikhail Murashko announced on Friday that the death toll had risen to 144 after one more patient succumbed to their injuries.
The authorities earlier claimed 11 suspects had been arrested previously, including four who allegedly carried out the attack. Those four, identified as Tajik nationals, appeared in a Moscow court on Sunday on terrorism charges and showed signs of severe beatings. One appeared to be barely conscious during the hearing.
The Investigative Committee had also claimed that the perpetrators of the attack received hefty financial support from Ukraine.
The committee said, "Confirmed information that perpetrators of the terrorist act had received significant sums of money and cryptocurrency from Ukraine, which were used in the preparation of the crime."
A group of terrorists, whom Russian President Vladimir Putin described as being radical Islamists, stormed a large music venue just outside of Moscow.
They went on a gun rampage, killing people on sight as they went towards the main hall, and set it on fire.
Russian officials also suggested that the terrorist attack at the Crocus City Hall may have been organised by Ukrainian special services who used the Islamists as proxies.
The gunmen left the venue after about 15 minutes and rushed away to a Russian region that borders Ukraine. They were arrested there on Saturday following a manhunt.