A well-known Russian historian has confessed to murdering his partner, his lawyer says, after he was found in a river with a backpack containing a woman's arms.
Oleg Sokolov, 63, was drunk and fell into the river as he tried to dispose of body parts, Russian media said.
Police then found the decapitated body of Anastasia Yeshchenko, 24, at his home in the city of St Petersburg.
Prof Sokolov is a Napoleon expert who has received France's Légion d'Honneur.
"He has admitted his guilt," his lawyer, Alexander Pochuyev, told AFP news agency, adding that the historian regretted what he had done and was now co-operating.
He lived with Ms Yeshchenko in a flat by the Moika river in St Petersburg, and they had been together for three years.
They were experts on French history: she was a postgraduate student at St Petersburg State University and had co-authored some works with him.
They both enjoyed wearing period costume, with him dressed as Napoleon, and participated in historical re-enactments.
Prof Sokolov was treated in hospital for hypothermia, after rescuers hauled him out of the icy water early on Saturday, and is now in police custody.
He is suspected of having killed Ms Yeshchenko with a sawn-off shotgun before dismembering the body. A stun pistol was found in the backpack along with the woman's arms.
The shotgun, knives, an axe and ammunition were also found in his apartment, Interfax news agency reported.
Выяснилось имя жертвы доцента СПбГУ. По данным СМИ, это 24-летняя выпускница Анастасия Ещенко. Вместе с историком Олегом Соколовым она работала над научным трудом о Наполеоне Бонапарте.— URA.RU (@ura_ru) November 9, 2019
Студенты говорят, отношения Соколова и Ещенко были романтическими. pic.twitter.com/e0IpUeFp0R
Prof Sokolov reportedly told police he had killed Ms Yeshchenko during an argument and had then sawn off her head, arms and legs.
He is said to have planned to get rid of the body before publicly taking his own life dressed as Napoleon.
Some students at the university, quoted by Russian media, described the professor as "eccentric" and a woman student said she had complained to the police about his behaviour previously.
A St Petersburg local councillor and former student of the professor, Vasily Kunin, has tweeted that he raised concerns about Prof Sokolov's behaviour but the university authorities did not act on his complaint.
More than 2,000 people have now signed an online petition demanding an inquiry into the university management and the history faculty's director.
According to students, quoted by AFP, Prof Sokolov enjoyed speaking French, did impressions of Napoleon, and called Ms Yeshchenko "Josephine" and asked to be addressed as "Sire".
What do we know about the victim?
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 three-year-long affair with the married professor 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.
Anastasia's brother told RBK Media that she called him in tears in the early hours of Friday morning, saying the couple had had a furious row sparked by the professor's jealousy. She was planning to spend the night in a student hostel.
At 01:49 the two spoke again, and Anastasia told her brother she was fine. It was the last anyone heard from her.
Prof Sokolov was also a member of France's Institute of Social Science, Economics and Politics (Issep), which on Saturday said it had removed him from his position on its scientific committee.
"We learn with horror... the atrocious crime of which Oleg Sokolov is allegedly guilty," it said in a statement. "We could not have imagined that he could commit such an odious act."
Issep was founded by Marion Maréchal, the niece of far-right National Rally party leader Marine Le Pen and a former lawmaker for the far-right National Front party.