HILLSBOROUGH COUNTY, Fla. — Nicole Nachtman's double murder trial continues Thursday with mental health taking center stage. 

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Nachtman, a former Florida State University student, is accused of killing her mother and stepfather in 2015 at their Carrollwood home. 

Prosecutor say she killed Myriam and Robert Dienes because her parents were demanding.  However, the defense says Nachtman had a psychotic breakdown after years of abuse by her mother. 

Dr. Charles Ewing, a Harvard University-Educated Forensic Psychologist, took the stand Thursday morning and told the court he believes Nachtman was mentally ill at the time of the murders and didn't know what she was doing or the consequences of her actions. 

Dr. Ewing's testimony is based on conversations he had with the psychologist who met with Nachtman, his own meetings with her, and his review of the more than 3,000 pages of case documents and files. 

Ewing is the second mental health expert to testify for the defense.  Prosecutors are expected to put their own mental health experts on the stand today. 

LIVE coverage from the courtroom from Spectrum News Reporter Dave Jordan: