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 on Saturday in the Moika River with the rucksack.

Police later found the body of his student in his apartment, Russian news reports said.

Russian Emergency rescuers and police investigators conducted searches on the Moika River, in Saint Petersburg, following the Sokolov's young lover and former student and dismembering her body in a grisly crime that sent shockwaves across Russia.

Search and rescue workers in the Moika River. Photo / AP
Search and rescue workers in the Moika River. Photo / AP

Sokolov, 63, who received France's Legion d'Honneur in 2003, was arrested on November 10, 2019 on suspicion of murder after he was hauled out of Saint Petersburg's Moika River with a backpack containing a woman's arms.

Lawyer Alexander Pochuev said Sokolov has signed a statement of guilt, and he was hospitalised Saturday for hypothermia but was taken to a police station Sunday for questioning.