Oleg Sokolov was reportedly drunk and fell into a river as he tried to dispose of severed body parts.

A prominent St Petersburg-based Napoleon scholar confessed to killing his young lover and former student and dismembering her body in a grisly crime that sent shock waves across Russia.

Oleg Sokolov, a 63-year-old history lecturer who received France’s Legion d’Honneur in 2003, was arrested on Saturday on suspicion of murder after he was hauled out of the icy Moika River with a backpack containing a woman’s arms.

“He has admitted his guilt,” Sokolov’s lawyer Alexander Pochuev said, adding he regretted what he had done and was now cooperating with police.

Sokolov was reportedly drunk and fell in as he tried to dispose of body parts.

After getting rid of the body, he reportedly planned to commit suicide at the Peter and Paul Fortress, one of the former imperial capital’s most famous landmarks, dressed as Napoleon.

Sokolov teaches history at St Petersburg State University, President Vladimir Putin’s alma mater, and was close to the Russian authorities.

He told investigators he shot and killed his lover during an argument and then sawed off her head, arms and legs, local media reported.

Pochuev suggested Sokolov may have been under stress or emotionally disturbed.

“He is an elderly person,” he said, adding he was being treated for hypothermia in a hospital.

Police discovered the decapitated body of Anastasia Yeshchenko, 24, with whom Sokolov had co-authored a number of works, and a blood-stained saw at his home.

Sokolov re-enacts the 1812 battle between Napoleon’s army and Russian troops in Maloyaroslavet in 2006 [File: Denis Sinyakov/AFP]

‘Simply monstrous’

The historian, who also taught at Sorbonne University, is the author of books on French Emperor Napoleon Bonaparte.

He acted as a historical consultant on several films and took part in historical re-enactments of Napoleonic wars.

Both he and his lover studied French history and liked to wear period costumes, with Sokolov dressing up as Napoleon.

Students described Sokolov as a talented lecturer who could impersonate the French emperor and his generals and a “freak” who called his lover “Josephine” and liked to be addressed as “Sire”.

“What happened is simply monstrous,” a St Petersburg State University lecturer said.

Speaking on condition of anonymity, he said Sokolov was dedicated to his work but was also emotionally unstable and abused alcohol.

His former student, Fyodor Danilov, said Sokolov was regarded as one of the university’s best lecturers but an eccentric man who at times yelled in French.

His relationship with Yeshchenko was an open secret, he said. “But everyone was fine with that, it was her own business,” said Danilov.

Many expressed dismay saying Sokolov had long been known for his hostile behaviour but officials had ignored complaints.

Vasily Kunin, who studied with the victim, blamed the university management.

“They did not pay attention to certain things. There was a certain policy of hushing things up,” Kunin said.

Media reports said Sokolov also beat up and threatened to kill another woman in 2008 but was never charged.