In detention of a group of perpetrators

In detention of a group of perpetrators

Employees of the Federal Security Service of the Russian Federation participated in the detention of a group of persons who committed numerous robberies against citizens and organizations.
Subsequently, one of the defense lawyers who defended the case in court challenged the lawfulness of the detention. He substantiated his application by the fact that the FSB of the Russian Federation took part in the detention, whose competence, in the opinion of the defense attorney, does not include the detention of suspected robberies.
Analyze the arguments of the defender. What regulations govern the activities of the bodies of the Federal Security Service?

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