Gombak police chief Samsor Maarof said investigations revealed that the baby died of severe injuries to the head caused by a blunt object.
He said 39 external injury marks were also found on the body.
“The babysitter had previously taken the victim to a nearby private clinic when she was unconscious and claimed that the victim had fallen while standing on the sofa at her house.
“The suspect claimed that she was unaware of the incident because she was in the kitchen,” he said when contacted here today.
Samsor said police arrested the babysitter and her husband as well as the baby’s mother, aged between 28 and 34, on Tuesday to facilitate investigations.
“The man has six previous drug-related criminal records,” he said.
The trio have been remanded until next Tuesday to facilitate investigations for murder.