There is a new UN Convention on Disappearances now open for signature.
Would Russia be willing to become a party? Some of its provision are these:
…”Accurate information on the deprivation of liberty of any person and on his or her whereabouts, including information on any transfer, the identity of those responsible for the deprivation of liberty, and the authority in whose hands the person has been placed, shall be made immediately available to the person’s counsel or to any other persons having a legitimate interest in the information.
In every place where persons deprived of liberty are held, States Parties shall maintain an official up-to-date register of such persons. Additionally, they shall maintain similar centralized registers. The information contained in these registers shall be made available to the persons and authorities mentioned in the preceding paragraph.
States Parties shall identify who is the responsible person in national law for the integrity and accuracy of the custody record. Without prejudice to the provisions of articles 1, 2 and 3 of this Convention, States Parties shall make it a criminal offence for the responsible person, as defined in national law, to fail to register the deprivation of liberty of any person or to record information which is or should be known to be inaccurate in the custody record.
States Parties shall periodically publish lists that name the places where persons are deprived of liberty. Such places must be visited regularly by qualified and experienced persons named by a competent authority, different from the authority directly in charge of the administration of the place.”…