Georgina died in hospital and posthumous toxicology tests showed she had received ketamine, an anesthetic drug often used in animal surgeries, that had not been prescribed by her treating doctors.
Protesters also gathered outside the mother’s home in the port city of Patras, 200 kilometres (125 miles) west of Athens, where police again intervened to maintain order.
A panel of senior coroners is leading a review into the death of the suspect’s two other children: a 3-year-old girl from liver failure in 2019 and a 6-month-old girl in 2021 from a suspected heart defect.
Tissue samples retained from the two girls are now being re-examined, authorities said.
The suspect has denied any wrongdoing and is expected to formally respond to the charges next week.