Norwegian Yasmin Chaudhry, 28, is accused of drowning her 21-month-old daughter from another relationship in a bucket of water on October 3, 2010.
Prosecutor Cecilie Schloesser Moeller claimed she was following live online instructions from her lover Ammaz Omer Qureshi, 35, who was in London at the time.
Schloesser Moeller called for a longer sentence for Qureshi, who she claims gave instructions to "discipline" the child by dunking her head in a bucket of water for interrupting their online chat.
The 28-year-old pleaded not guilty to first-degree murder but admitted to assaulting the child. Her lover denied any involvement in the crime.
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The murder took place, according to investigators, in the early hours of the morning, after the toddler interrupted the couple during an online video chat.
The mother plunged the child's head under water twice until she lost consciousness.
Chaudhry then called emergency services and reported the incident as an accident. The child died in hospital the following day.
Qureshi allegedly carried out the abuse on instruction from Qureshi, who also sometimes watched via the Internet.