The announcement came after a meeting of chief investigators from Chechnya, Dagestan and Ingushetia, ITAR Tass reported.
"It is not a secret and not the news that militant leader Doku Umarov is behind all this," said Ingushetia President Yunus-Bek Yevkurov after the meeting.
He claimed that a group led by Emir Artur Getagazhev and other people were involved in the bombing.
A suicide bomber blew himself up on Sunday in Ingushetia at the funeral for a police officer who had been killed the night before by militants.
2014: The Year in Music [PHOTOS]