A punk rock musician known as Pussy who cut off his girlfriend's head and had sex with it while wearing one of her dresses has been declared insane.

Aleksandr U., 23, murdered his girlfriend, 22-year-old Viktoria V., in the city of Voronezh, in Russia's south-western Voronezh Oblast, in July last year.

Police who discovered the decapitated body of the young woman then also found her head, which Aleksandr had used to have sex with.

Girlfriend: Aleksandr U., 23, murdered his girlfriend, 22-year-old Viktoria V., in the city of Voronezh, in Russia's south-western Voronezh Oblast

Punk rock band: Aleksandr's fellow band members threw him out after they discovered he liked to wear women's clothes

He apparently liked dressing up in women's clothes and masturbating, and when his friends in the punk band discovered his fetish, they threw him out.

It is believed that when his girlfriend discovered he was wearing her clothing and makeup, she had tried to dump him. He murdered her instead.

His fellow band members confirmed they had expelled him because of his habit of wearing female clothing.

Investigation: Instead of being prosecuted, Aleksandr was declared mentally ill and is in a psychiatric institute

Discovery: When Viktoria (left and right) found out Aleksandr wore women's clothes, she tried to dump him

Killer: Aleksandr, who killed his girlfriend in July, has been declared mentally ill and has not been prosecuted

They said they had tried to talk to him about it but he had always managed to avoid the subject.