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 Schløsser Møller claimed she was following live online instructions from her lover Ammaz Omer Qureshi, 35, who was in London at the time.
Schløsser Møller 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.
She demanded 16 years of imprisonment for Chaudhry, two years less than her lover, because she had helped the investigation.
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.
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.
The duo are also accused of "regularly" torturing the girl, when they allegedly forced her to swallow chili powder, gagged her with adhesive tape, slapped her in the face and forced her to take cold showers and sleep on the floor.
Qureshi allegedly carried out the abuse on instruction from Qureshi, who also sometimes watched via the Internet.