Police in Tula, a small city some 200km to the south of Moscow, have detained a man on suspicion of the murder of a family of five, including three children.

The bodies of the victims - a 35-year-old mother, her three boys aged four, five and nine, and their grandmother - were discovered stacked up in a bathroom on Monday evening after neighbors complained of an unpleasant smell. Police believe they were beaten to death with a blunt instrument - possibly a hammer - on the night of July 25.

Initial reports suggested sect involvement or a business dispute.

Police said on Thursday, however, that the suspect was a 26-year-old man who first made the acquaintance of the family when he fixed their computer in 2008.They say the motive for the crime was robbery.

A police spokesman said earlier on Thursday that the suspect was the mother’s “common-law husband.”

The murders have made headlines in Russia, and echo last year’s killings in a village in south Russia’s Krasnodar region, when 12 people, including four children, were slaughtered by a criminal gang.