Alyssa Bustamante's prescription for Prozac may have helped lead her to killing Elizabeth Olten, 9, a consulting psychiatrist testified Monday afternoon.
And Bustamante's grandmother told Cole County Circuit Judge Patricia Joyce she was worried about Alyssa's mood swings as her dosage changed several times.
Karen Brooke has been the teen's legal guardian for nearly 11 years.
She told Joyce on Monday the girl had an emotional roller-coaster childhood as her mother and father - both regular drug users - popped into, then out of, her life.
Alyssa was "a very quiet child" who one time had witnessed her mother passed out on the floor from a drug overdose, while the family still lived in the state of California - and later acted like her younger, twin brothers' mother when Brooke also gained the boys' guardianship.
As she entered eighth grade in 2007, Brooke said, school counselors recommended Bustamante, then 13, get professional counseling after the girl's friends reported the teen was cutting herself.