A ninth person accused of organizing an attack claimed by the Islamic State group that killed more than 140 people in a suburb of Moscow has been taken into custody, Russian justice announced on Friday, as quoted by AFP.

Exactly one week ago, armed men opened fire on the Crocus City Hall concert hall near the Russian capital, and then set it on fire.

Russian authorities announced the death toll at 143 on Wednesday, and Russian Health Minister Mykhailo Murashko said on Friday that one more person had died. Dozens of victims are still in hospital.

The four alleged attackers were arrested along with several suspects accused of helping them.

The ninth suspect, Nazrimad Lutfoluy, was detained on Friday, the press service of the Moscow courts reported.

Like the alleged attackers, he is from Tajikistan, a former Soviet republic in Central Asia.

The authorities do not specify what role he is accused of.

He is being held at least until May 22.

This attack became the bloodiest in the last twenty years in Russia and the most serious for the responsibility of the jihadist group “Islamic State” (ISIS) on the territory of Europe.

On Friday, the Islamic State group confirmed the arrest of four of its members, whom it called the perpetrators of the attack.

Despite these clear claims of the jihadists, the Russian authorities persistently maintain ties with Ukraine.

CNN writes that the security services of the Kremlin knew about the threat of ISIS a few days before the armed attack on a concert hall near Moscow, Russian intelligence documents obtained by a British investigative organization show.

According to the London-based Dossier Centre, the documents show that ethnic Tajiks radicalized by ISIS-K – the Central Asian branch of the ISIS terrorist group – may have been involved.

• On the same topic: Moscow attack: ISIS says there was ‘reason’ why four attackers ‘quickly left’ concert hall and caused no more casualties

The Kremlin is trying to blame Ukraine

Russian investigators said Thursday they had found evidence that the concert hall attackers had ties to “Ukrainian nationalists,” a claim the United States quickly dismissed as unsubstantiated propaganda.

“Working with detained terrorists, checking the technical equipment seized from them and analyzing data on financial transactions made it possible to obtain evidence of their connections with Ukrainian nationalists,” the Investigative Committee of Russia wrote in Telegram on Thursday.

The head of the Federal Security Service (FSB) Oleksandr Bortnikov said on Tuesday that the terrorist attack was prepared by radical Islamists with the support of Ukrainian special services.

And the Secretary of the Security Council of Russia, Mykola Patrushev, said on Tuesday that Ukraine was “of course” behind the terrorist attack, Reuters reports.

There is no evidence of Kyiv’s involvement in Friday’s attack on the outskirts of Moscow, four people closely connected to the Kremlin said.

In addition, almost no one in the political and business elite of Russia believes that Ukraine is behind the attack, the news agency was informed.