The naked body of a Russian scientist was found in her flat with her thumb severed.
Russian biochemist Ekaterina Antontseva, 34, was believed to have been strangled or suffocated, say law enforcement sources.
Her corpse was discovered by her boyfriend, a construction entrepreneur, on his return from a business trip.
A male computer game fanatic identified only as Artyom, 36, has been detained on suspicion of murdering the lecturer who worked at St. Petersburg Technological Institute and part-time as a model.
Police found the severed thumb of Ms Antontseva, who taught at St Petersburg State Institute of Technology, at Artyom’s home.
The suspect allegedly used the fingerprint to gain access to her phone, from which he sent messages saying she was feeling ill and would not come to work.
He also deleted messages between himself and the victim, police believe.
One theory is he owed the woman money and that they had argued about repaying it.
She was killed last Thursday and gaps in the doors and windows of her flat were sealed to prevent odour from being noticed by neighbours, reports say.
According to pdmnews.ru, Dr Mark Shamtsyan, professor at St Petersburg State Institute of Technology, said: “She was a very good person, very sympathetic, we all loved and respected her, and now it’s hard to talk about it.
“She also had hobbies, she was engaged in photography. But she also loved her work, she liked working with students. She was a good researcher and teacher.
“She worked for us part-time and did not come every day: two, sometimes three days a week. She was absent at a time when she should not be.
“When we realized, she did not come, we began to look for her, it was already Friday. And on the weekend we received information from the investigating authorities.”
Russia’s Investigative Committee is conducting a murder investigation.