Maria Plenkina has been detained after going on a week-long partying 'spree' leaving her daughter to die alone of starvation and neglect.
The tragic girl Kristina was found by her grandmother Irina Plenkina, 47, when she brought a birthday present for the girl's third birthday.
Irina immediately called the ambulance and police but the girl was pronounced dead at the scene.
The distraught grandmother said that Maria had been in touch with her daily on social media telling her that she and the girl were 'fine'.
In reality the mother had locked the door on her daughter, turning off the water so she could not even drink, according to the Russian Investigative Committee.
The mother has been detained for two months and is under investigation for the 'murder of a child using extreme cruelty'.
The mother was 'not there for a week - from February 13 to February 20', said the committee which has taken charge of the murder investigation.
'She doesn't even cry, and shows no regret.
'She just says in cold blood: "Yes, I left, I closed off the water and left the child without water and food."'
Maria Plenkina, 21, left her daughter to starve over her third birthday while she went out on a partying spree with her friends in the Russian city of Kirov.