MOSCOW — Police in the Russian city of St. Petersburg plan to interrogate a prominent professor who has been detained on suspicion of killing a female student after he was pulled from a frigid river with a backpack containing severed arms.

Oleg Sokolov, a history professor at St. Petersburg State University who is an 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.

In this Monday, Jan. 7, 2013 photo, Oleg Sokolov, a history professor at St. Petersburg State University, wears a 1812-era French army general's uniform during a reenactment of the French Invasion of Russia in 1812, during celebrations to mark the Russian Orthodox Christmas in St.Petersburg, Russia. (Dmitri Lovetsky/AP)
In this Monday, Jan. 7, 2013 photo, Oleg Sokolov, a history professor at St. Petersburg State University, wears a 1812-era French army general's uniform during a reenactment of the French Invasion of Russia in 1812, during celebrations to mark the Russian Orthodox Christmas in St.Petersburg, Russia. (Dmitri Lovetsky/AP)

Lawyer Alexander Pochuev said Sokolov has signed a statement of guilt, the Russian media reports said.

Sokolov was hospitalized Saturday for hypothermia but was taken to a police station Sunday for questioning.

Reports said Sokolov had been awarded France’s Legion of Honor for his work.