MOSCOW (AP) — Police in the Russian city of St. Petersburg are planning to interrogate a prominent professor who has been detained on suspicion of killing a female student after being pulled from a frigid river with a backpack containing severed arms.

Oleg Sokolov, a history professor at St. Petersburg State University who is expert in French revolutionary military history, was found Saturday in the Moika River with the rucksack. Police later found the body of his student in his apartment, Russian news reports said.

Lawyer Alexander Pochuev said Sokolov has signed a statement of guilt, the reports said. Sokolov was hospitalized on Saturday for hypothermia but on Sunday was taken to a police station for questioning.

Reports said Sokolov had been given France's Legion of Honor award for his work.