WOODLAND, Calif. — A defense psychiatric expert testified Wednesday in Yolo County Superior Court that former UC Davis student Carlos Dominguez suffers from schizophrenia and was experiencing florid psychosis at the time of the 2023 Davis stabbings, rejecting the theory that his condition was caused by cannabis-induced psychosis.
Dominguez, a former UC Davis student, is charged with two counts of second-degree murder and one count of attempted murder in connection with the April 2023 stabbing attacks in Davis. His first trial ended in a mistrial last June after jurors acquitted him of first-degree murder but were unable to reach verdicts on the remaining charges.
Dr. Stephen Weiner, who was called to the stand by Deputy Public Defender Dan Hutchinson on behalf of the defense, testified about his medical credentials and psychiatric expertise, as well as his familiarity with Dominguez and the information in the case before being recognized by Judge Samuel T. McAdam as an expert witness in the retrial.
While establishing his expertise in the case, Dr. Weiner stated that he had reviewed Dominguez’s records from Yolo County Jail and Atascadero State Hospital, as well as testimony from Dominguez’s family members, roommates, arresting officers and other expert witnesses, in addition to watching seven hours of footage from Dominguez’s arrest and interrogation in May 2023.
DPD Hutchinson asked Dr. Weiner about his meetings with Dominguez, to which he responded that he met with Dominguez on four separate occasions between November 2024 and May 2025.
Dr. Weiner said that during those meetings he evaluated Dominguez for signs of mental illness, explaining to the court the symptoms of schizophrenia, including illusions, hallucinations, blunt affect, lack of emotion, stiff posture and the ability to sit still for hours at a time.
Hutchinson asked, “Based on everything you’ve reviewed, does Dominguez suffer from mental illness?” Dr. Weiner replied yes, specifying that the mental illness was schizophrenia.
Going deeper into the symptoms of schizophrenia, Dr. Weiner explained that people who suffer from schizophrenia often have disorganized speech, an inability to maintain eye contact and difficulty with abstract thought.
Hutchinson then asked Dr. Weiner if he was familiar with the term “avolition” in connection with schizophrenia, to which Dr. Weiner replied that he was, explaining that avolition can be described as “lacking will or intention.” Dr. Weiner went on to say that people suffering from schizophrenia often lack the initiative to eat or shower, displaying an inability to care for themselves or others.
Dr. Weiner also stated that when Dominguez was arrested, he displayed moderate cannabis use disorder, explaining that people with schizophrenia often have a co-occurring substance use disorder.
Dr. Weiner testified that he believes Dominguez did not suffer from cannabis-induced psychosis at the time of his arrest, explaining that Dominguez’s mental state gradually deteriorated over a two-year period, with symptoms progressively worsening, whereas cannabis-induced psychosis is more acute and its symptoms appear more erratically.
Going more in depth on cannabis-induced psychosis, Dr. Weiner stated that its symptoms usually dissipate within days to weeks after cannabis is last ingested. He went on to say that Dominguez’s symptoms of mental illness persisted for six months after his last reported cannabis use.
Dr. Weiner said that Dominguez previously told him, “Supernatural entities were trying to take hold of him,” explaining that people with schizophrenia often face a higher risk of violence when they perceive a threat like that.
Hutchinson then asked Dr. Weiner what factors could lead to schizophrenia in a person, to which Dr. Weiner responded that schizophrenia usually results from a genetic predisposition, such as a family history, combined with traumatic life experiences and environmental factors.
Hutchinson went on to ask whether “sexual abuse, physical abuse from a parent, or witnessing domestic abuse” could be examples of a traumatic environment, to which Dr. Weiner agreed.
Hutchinson continued by outlining the manner in which Dominguez first emigrated to the United States, explaining that he was smuggled into the country by coyotes, detained by immigration authorities and eventually reunited with his parents in Oakland after years apart.
Hutchinson asked, “Could this constitute severe childhood trauma?” Dr. Weiner replied, “Yes.”
Hutchinson then shifted the questioning from Dominguez’s childhood and asked whether Dr. Weiner was familiar with what is known as “florid psychosis.”
Dr. Weiner said he was familiar with the term and explained that it is used to describe someone who is severely mentally ill and displaying profound symptoms of psychosis.
Referring back to Dominguez’s seven-hour interrogation after his arrest, Dr. Weiner pointed to the moment when Dominguez expressed concern about having to study for classes, stating that the exchange demonstrated “a core component of psychosis” because Dominguez was unable to understand the gravity of being suspected of murder.
DPD Hutchinson also asked Dr. Weiner about Dominguez incorrectly stating his mother’s name, his phone number and his roommate’s name during the interrogation. Dr. Weiner testified that he believed those inaccuracies were not an attempt to conceal his identity but rather symptoms of schizophrenia causing disorganized thought and speech.
To conclude his direct examination, DPD Hutchinson asked Dr. Weiner, “Based on your opinion, was Dominguez in a state of florid psychosis?” Dr. Weiner replied, “Yes.”
Hutchinson then asked whether Dominguez “exhibited positive symptoms of schizophrenia?” Dr. Weiner again replied, “Yes.”
Following Hutchinson’s direct examination, Deputy District Attorney Matt De Moura questioned Dr. Weiner about his experience treating individuals with schizophrenia who also use cannabis. Dr. Weiner told De Moura that he has frequently treated people whose cannabis use exacerbated their schizophrenia symptoms.
De Moura then asked whether it was important to consider other factors when diagnosing schizophrenia, asking Dr. Weiner whether it “take[s] a lot to determine mental illness?” Dr. Weiner replied, “Yes.”
The retrial is scheduled to resume Thursday before Judge McAdam in Yolo County Superior Court.
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