A young mum abandoned her two-year-old daughter because 'she wanted to spend more time with her boyfriend', according to police.
Maria Rudnitskaya, 21, left the toddler alone after taking her to a health clinic.
The traumatised girl waited for her mother's return but never came back, reports say.
Medical staff grew concerned over her welfare and asked her where her parents were.
The child was examined by doctors and taken to an infectious diseases hospital with a cold.
Meanwhile, police tracked down the girl's mother after spotting her in surveillance camera video.
The footage showed Rudnitskaya wearing a medical mask and entering the doctors clinic while carrying the toddler in her arms.
The mother left the unnamed girl sitting on a bench and exited the building just minutes later.
Rudnitskaya was found within 24 hours and was later interrogated by police
The mother confessed in full saying that she abandoned her daughter because she wanted to spend more time with her boyfriend.
The mother also said that she was tired of taking care of the girl, authorities say.
An Investigative Committee spokesperson said: "After leaving her daughter, the mother came out of the polyclinic and approached her boyfriend waiting outside.
"Then they went home in an attempt to get rid of the girl.
"The mother was wearing a medical mask in order not to be identified."
Police have issued charges over abandoning a child and failure to fulfil parental duties against Rudnitskaya.
Reports say the woman, who is from Ukraine, has been living in Moscow for five years.
Recently she divorced her husband and moved in with a new 27-year-old boyfriend.
Arina's grandmother Natalia Rudnitskaya now wants custody of the girl after learning about the incident on the news, local media reported
A source at Investigative Committee said: ''The grandmother saw the girl in news on television and contacted the police.
''She wants to take the girl home but it is not possible until the investigation is finished.''
The girl will be placed in an orphanage after her release from hospital, local media reported.
The suspect now faces up to four years in prison if found guilty.
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