Kaitlyn Renee Higgins was arrested on Tuesday at her home in Louisville
Police said they found her 10-year-old son Kyon Higgins Jr dead in the trunk of her car
Higgins allegedly admitted to shooting the boy after trying to cut out his tongue
She was charged with murder stemming from domestic violence and tampering with evidence
Kyon's babysitter said she suspected Higgins abused the boy in the past