San Bernardino County Sheriff's officials said 29-year-old Jakee Contreras, the mother of Duke Flores, was arrested Saturday after being questioned by detectives. The boy's aunt and Jakee's twin sister, Jennifer Contreras, was also arrested for investigation of murder.
A family member requested a welfare check on Thursday night, and when deputies went to the boy's home the mother told them he hadn't been seen for two weeks.
Authorities did not release a motive, and said they were still looking for the child.
Family members told KABC-TV the boy has autism and plan to convene a search for him.