Police cracked the case within 24 hours after the child went missing as was initially claimed by the accused, identified as Mangal Pradip Borse.
"Borse had tried to mislead the police by claiming that the girl, Ketki Kapil Hirey, was kidnapped by an unknown woman last morning, following which police registered a case under appropriate sections of IPC and launched a search" said senior inspector I R Andhalkar of Badlapur (east) police station.
The child, suffering from cerebral palsy, used to stay with her grandparents since her parents are working.
According to the police officer, the accused was fed up with the condition of the child and was worried about her future.
"The accused allegedly took the girl with her to a nullah in an autorickshaw last morning and murdered her by drowning her," Andhalkar said, adding that the woman then approached the police claiming that her granddaughter was abducted.