A suspected paedophile knifed to death his own son then daubed the message in his boy's blood: 'I gave you life, I will take it.'
Savva Nikitin killed his wife, Maria, who had just found out about him 'raping' the five-year-old child and threatened to tell police in Moscow, Russia.
The 34-year-old is said to have called Maria 'Judas' in a sign written in blood in their apartment.
Nikitin stabbed his son named Mark at least 62 times with a knife and a screwdriver, say law enforcement sources in Moscow. He later confessed to police that he had sexually abused the youngster.
The son of famous Crimean author Alexander Nikitin, he tried but failed to kill himself with a knife.
During a confession, he later told officers he had killed his son and his wife, say Russian reports.
The chilling quote written in blood on the floor of his flat - 'I gave you life, I will take it' - is from nineteenth century Russian writer Nikolai Gogol in novel Taras Bulba.
He also daubed 'Masha (Maria) is Judas' on a windowsill in the family's Moscow flat.
The 29-year-old woman had fought back during a fight and left numerous scratches on her husband's body before she was strangled, say reports.
In hospital Nikitin confessed to state investigators that he had had 'perverted' sex with his son, reported Moskovsky Komsomolets newspapers and other sources citing Russian law enforcement.
He told them that his wife had found about about his 'intimate relations' with the boy.
The unemployed man is under 24-hour armed police guard in a Moscow hospital. A video from Moskva24 news channel shows blood in the flat.
The couple moved to Moscow from Crimea in 2014 when the Black Sea province was annexed by Vladimir Putin's troops.
They were described as 'happy' and 'friendly', living in the Medvedkovo suburb of Moscow.
The Russian Investigative Committee confirmed a criminal probe into the two deaths.
Nikitin faces up to 20 years in jail if convicted of the two murders to which he is reported to have confessed.