A 50-year-old woman was arrested for allegedly flinging her toddler step-granddaughter from her 6th floor flat in Malad in the metropolis, police said on Monday.
The body of 2-year-old Jiya Ansari was found in a pool of blood in the early hours of Saturday and family members at the time had told police the incident may be an accident, an official said.
However, sustained questioning of each of them led to Ruksana Obedullah Ansari confessing to her role in killing the toddler, he said.
He said Jiya's father, Ejaz Ansari, was the accused's step-son.
"Jiya and the Ruksana's daughter's son would fight often during playing. The accused would threaten Jiya's mother Saniya that she would kill Jiya if the fights didn't stop. After a quarrel with Saniya, Ruksana threw Jiya from the kitchen window on Saturday, killing the child instantly," a Kurar police station official said.
Ruksana has been charged with murder and will be produced in court on Tuesday, said Senior Inspector Babasaheb Salunkhe of Kurar police station said.