WOODLAND, Calif. — Expert witness clinician Dr. Siegel returned to the stand Friday afternoon in the retrial of Carlos Reales Dominguez, providing extensive testimony about bipolar disorder, schizophrenia and the effects of cannabis use on severe mental illness during questioning by both the prosecution and defense at Yolo County Superior Court.
The cross-examination of Dr. Siegel took place June 26 at the Yolo County Courthouse in Woodland. Dr. Siegel, who previously testified as an expert witness, answered a series of questions under oath posed by Deputy District Attorney Alex Kian after first being questioned by Deputy Public Defender Dan Hutchinson.
The accused, Carlos Reales Dominguez, is charged with two counts of second-degree murder in the fatal stabbings of David Breaux and Karim Abou Najm, as well as one count of attempted murder in the stabbing of Kimberlee Guillory, who survived after suffering critical injuries during the 2023 attacks. He is also charged with enhancements for the use of a deadly weapon and circumstances in aggravation.
During his testimony, Dr. Siegel discussed the severe mental health condition known as bipolar disorder. He described some of the common symptoms associated with the condition, stating, “Bipolar means two poles, two directions, and it reflects changes in affective states…such that people have periods of depression, or major depression, interspersed with periods of what is called mania, in which case they have elevated mood.”
“Some of the other symptoms of mania are a lack of need for sleep…an influx of thought that’s uncontrollable, like a racing mind, and risky behavior…[like] a period of poor judgment when people will exhibit a variety of risky behaviors and often has grandiose delusions,” he concluded.
DPD Hutchinson then asked the expert witness whether, in his experience, there were people who suffer from bipolar disorder who go years without seeking treatment or being fully diagnosed.
“Yes,” Dr. Siegel responded.
In turn, DDA Kian asked the expert witness whether he had ever heard the term “goal-directed behavior.” He responded in the affirmative, stating that it refers to performing tasks with a particular outcome in mind and acting toward that outcome. He explained that it is significant in the psychiatric community; however, it is not specific to any one mental illness.
DDA Kian then shifted the focus of the testimony to the chronic brain disorder schizophrenia. He asked Dr. Siegel whether people with the mental health condition were capable of performing goal-directed behavior.
“Many people with schizophrenia much of the time can do that. So there’s a continuum of severity across people, but there’s also fluctuation over time,” he stated.
“Understood,” DDA Kian responded.
He then addressed other symptoms associated with schizophrenia, stating that both hallucinations and delusions were common symptoms. He asked Dr. Siegel whether an individual exhibiting those signs is affected by environmental factors.
“How do these manifestations happen?” he clarified.
“So there’s two ways I’d like to address that. One is the extent to which people who are experiencing symptoms can be very sensitive to their environment. Sometimes a person might be sort of going along, they’re in treatment, their dose is stable and they’re well and then they have an acute exacerbation. … But the environment fuels to some extent the symptoms,” Dr. Siegel stated.
He then provided the court with a detailed explanation of what an individual diagnosed with schizophrenia experiences on a daily basis. He informed DDA Kian that “hearing voices” was a common symptom of the disorder.
“When you talk about schizophrenia, [or] when a person says they have schizophrenia, does that mean that they are always psychotic?” asked DDA Kian.
“No,” Dr. Siegel stated.
He continued by explaining that the condition is a trait, “something that is like height. You have it.” He differentiated that psychosis is more like a state, saying “it comes and goes.”
He argued that psychosis, on its own, is not exclusive to schizophrenia and is present across a number of disorders.
DDA Kian then asked Dr. Siegel to shift his focus to substance use—specifically cannabis—in relation to schizophrenia.
“You would agree that substance use with somebody who may have been predisposed to schizophrenia can exacerbate the symptoms of schizophrenia,” DDA Kian stated.
The expert witness responded in the affirmative, explaining that heavy cannabis use can cause a fourfold increase in the manifestations of the condition.
“Substance use can impact dormant schizophrenia at an increased rate,” he stated.
Dr. Siegel told the court that symptom levels fluctuate with treatment but also with environmental factors. He explained that those environmental factors can include exposure to cannabis, which can exacerbate symptoms.
“Someone can have schizophrenia, they might have a mild, moderate, or severe case that can be treated and kept in check, but then you layer cannabis or another drug on top of that and it changes the balance, the homeostasis. You’ve got disease, you’ve got treatment, and now you have another thing and you tip the balance,” he stated.
DDA Kian then concluded his cross-examination.
Dominguez is scheduled to return to court for the resumption of his trial Monday, June 29, at 9:30 a.m.
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