Closing arguments were presented Thursday in Lindsay Clancy’s murder trial in Massachusetts after 21 days of testimony.

The jury, made up of nine women and three men, began deliberations Thursday afternoon and will resume Friday morning.

Clancy has pleaded not guilty to charges of first-degree murder in the deaths of her three children, 5-year-old Cora, 3-year-old Dawson and 8-month-old Callan.

Prosecutors argue that Clancy planned the killings, while her defense claims she was overmedicated and suffering from postpartum psychosis and should not be held criminally responsible, CBS News has reported.

If convicted of first-degree murder, Clancy faces life in prison without parole, while a finding that she was not criminally responsible would result in her being sent to a state psychiatric hospital.