Lindsay Clancy: Day 10 of Trial of Mom Accused of Killing 3 Children, Watch Live

The triple-murder trial for Lindsay Clancy is entering its third week ... and a psychiatrist who treated the Massachusetts mother in the weeks leading up to her children's brutal deaths is set to testify.

Clancy is accused of strangling her three children ... 5-year-old Cora, 3-year-old Dawson and and 8-month-old Callan ... with elastic workout bands at her Duxbury home -- before she tried to kill herself.

Her defense team is attempting to make a case for insanity, arguing Clancy was experiencing postpartum psychosis when she allegedly brutally killed her kids.

Clancy's ex-husband is helping with that defense ... and he's already testified.

A forensic toxicologist took the stand last week and told the jury she had several medications in her system when she allegedly killed her children and attempted suicide.

We've also heard testimony that Clancy called the suicide hotline twice before the alleged triple-murders.

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