Russian prosecutors have accused a renowned historian of murder after he admitted shooting and then dismembering his student partner in St Petersburg.

Oleg Sokolov, 63, was rescued drunk from the Moika river in the city early on Saturday and was found to have a woman’s arms in his backpack.

Police later found other body parts further downriver and in his flat, identified as Anastasia Yeshchenko, 24. She had been living with him.

He sobbed in court, saying: “I repent”.

Mr Sokolov was ordered into pre-trial custody for two months.

In court he admitted shooting Ms Yeshchenko four times with a sawn-off shotgun, then chopping up the body with a saw and kitchen knife. A stun pistol was also found in the backpack.

Divers are still searching for more remains: he is suspected of having dumped two more bags in the river.

He sobbed so loudly in court that at one stage the judge adjourned proceedings.

Mr Sokolov is a Napoleon expert who has received France’s top state award, the Legion d’Honneur. He has written dozens of historical research papers, and Ms Yeshchenko, a postgraduate student, co-wrote some of them.

He organised Napoleonic re-enactments – playing the role of Napoleon himself – and she participated.

Mr Sokolov said the pair had been living together for five years, though other reports described it as a three-year relationship.

The case has triggered outrage: women’s rights activists say it illustrates widespread indifference towards sexual harassment and domestic violence in Russia.

An online petition has collected more than 7,500 signatures, demanding that the managers of St Petersburg State University, where he lectured, be dismissed.

It accuses them of having ignored previous students’ complaints about Mr Sokolov.

In court he alleged that Ms Yeshchenko had attacked him with a knife – and at that point he shot her – during a blazing row.

“This girl, who seemed like a beautiful ideal to me, turned into a monster,” he alleged. He said she was jealous of his children from a previous marriage.

Her parents rejected his version of events.

The Kremlin has described it as a “monstrous” crime. President Vladimir Putin graduated from St Petersburg State University.

The university has now dismissed Mr Sokolov and he has also been removed from a post at France’s Institute of Social Science, Economics and Politics (Issep).

Mr Sokolov was treated in hospital for hypothermia after rescuers hauled him out of the icy water on Saturday. Ms Yeshchenko was killed in his flat on Thursday night.

Her head was found in the flat, as well as the shotgun, knives, an axe and ammunition, Russian media report.

He is said to have planned to get rid of the body before publicly taking his own life dressed as Napoleon.

• Teenage Russian ‘abuse victims’ face jail
• The dark reality of Russia’s domestic violence laws
• ‘I want to stand up for every woman experiencing abuse’

A St Petersburg local councillor and former student of the professor, Vasily Kunin, has tweeted that he raised concerns about Mr Sokolov’s previous behaviour but the university authorities did not act on his complaint.

According to students, quoted by AFP, Mr Sokolov enjoyed speaking French, did impressions of Napoleon, and called Ms Yeshchenko “Josephine” and asked to be addressed as “Sire”.

Ms Yeshchenko moved to St Petersburg to study from Krasnodar region in southern Russia, and was a postgraduate student at the time of her death.

“She was quiet, sweet and always the ideal student,” an acquaintance told Russia’s RIA news agency. “Absolutely everyone knew about their relationship.”

Russian media report that her mother is a police lieutenant colonel and her father a school PE teacher. A brother once played as a goalkeeper for the national junior football team.

The papers here are full of details of this murder, the tragic and gruesome tale of a brilliant and beautiful young student shot and dismembered by her 63-year old former professor-turned-lover.

In these accounts, Oleg Sokolov emerges as a historian whose interest in Napoleon bordered on the obsessive. He had a glittering CV as a respected expert on French military history, who had been visiting professor at the Sorbonne. He was also a major figure in the world of historical re-enactment.

One friend told Komsomolskaya Pravda newspaper the professor had organised costume balls and picnics, as well as recreating battles. But organisations he’s been linked to have now scrubbed his name from their websites.

Anastasia Yeshchenko’s affair with the married lecturer was common knowledge at the university. Friends say she was a top student, highly intelligent, who shared her lover’s passion for Napoleonic history. One person described the professor as “eccentric but not aggressive”; others claimed he considered himself Napoleon reincarnated.