Paramedics confirmed the 21-day-old’s death at the scene after falling onto concrete from a residential building in Vasilyevo village, Russia.

‘A criminal case has been opened over the death of the infant,’ said the Russian Investigative Committee.

Their mother now faces prison.

Investigators are examining whether the five-year-old was ‘jealous’ of the new baby, and the mother’s motive for leaving her daughters home alone.

One report said she was visiting a friend.

‘The actions of the parents who left the children unattended, as well as other possible scenarios, are being investigated.’

A report citing local sources said: ‘The girl was upset that there was another child in the flat, and out of jealousy, she threw the infant out of the window.’

District chief in Zelenodolsk, Tatarstan, Mikhail Afanasyev, said: ‘Law enforcement officers are now investigating the situation.

‘I express my condolences to