Lindsay Clancy Trial

Shocking testimony in the Lindsay Clancy triple-murder trial ... a forensic toxicologist says she had several medications in her system when she allegedly killed her children and attempted suicide.

Four psychiatric medications were found in Clancy's blood ... two separate antidepressants, a mood stabilizer, and finally, quetiapine -- a drug used to treat schizophrenia, bipolar disorder, and major depressive disorder.

The expert, forensic toxicologist Justin Brower, told the court only one of the four prescriptions was at an elevated level ... that being the quetiapine, but it wasn't at a "toxic concentration" or "suicidal concentration," per The Guardian.

The murder trial for Lindsay Clancy enters day 2 ... and her ex-husband Patrick took the stand to reveal the horrifying scene he saw when he found the children's bodies.

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

Opening statements were Monday in a horrific case ... and Clancy's ex-husband Patrick took the stand, and he defended her.