HOUSTON, Texas (KTRK) -- Josh Armstrong, the older half-brother to A.J. Armstrong, an empathetic son, who was once passionate about music and devoted to his siblings, lost touch with reality after his parents were murdered on July 29, 2016.
That's what prosecutors tried to convey to the jury on day nine of A.J. Armstrong's third capital murder trial.
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During the two years that followed the killings, Josh Armstrong spiraled from depression to full-blown schizophrenia, ultimately resulting in a psychotic breakdown, concluded Dr. Ian Lamoureux, a psychiatrist testifying for the state.
Lamoureux walked jurors through Josh's medical records. A.J. Armstrong's attorneys have long argued that Josh's mental decline started before Dawn and Antonio Sr. were shot to death.
In both of A.J.'s previous capital murder mistrials, the defense has pointed the finger at Josh as an alternative suspect in the double homicide. That's not, of course, how prosecutors see it.
"Josh Armstrong is another victim of these murders," Lamoureux said on the stand. "He will be living with this for the rest of his life."
Lamoureux said he drew his conclusions after reviewing police reports, hundreds of pages of Josh's medical history post-murders, and text messages between Josh and his parents and A.J. and his parents leading up to July 2016.
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"Texts are a modern insight into peoples' souls. They often have no filter," said Lamoureux. "Josh was thoughtful, empathetic, loved his mother deeply. (She) leaned on Josh for emotional support because of A.J.'s behavior. Josh would build her back up when she was feeling low."
Lamoureux told the jury that the texts between A.J. and Dawn, in contrast, "were almost always manipulative." A.J. appeared "dismissive and devoid of any empathy," he testified, directing the jury to Armstrong's "yes ma'am, no ma'am," responses to his mother.
Days earlier, prosecutors introduced these texts. The cell phone records show Armstrong would often answer his mother this way after expressing disappointment in some of A.J.'s decisions.
Prosecutor John Jordan asked Lamoureux, "(Couldn't) that be just being polite?"
"Not polite, dismissive of the pain Dawn says she was experiencing," Lamoureux said.
Defense attorney Chris Collings pointed out Lamoureux didn't read all the family texts.
"You don't know how they got along daily," Collings said during cross-examination. "A gross misinterpretation of the family dynamic."
The first documentation of Josh seeking treatment for his mental health happened on December 19, 2016, nearly five months after the murders.
Josh voluntarily checked himself into Ben Taub Hospital, according to medical records. He was 21 years old.
The records state that Josh was "constantly worried and paranoid about the suspects coming after him" and that he was using "drugs and marijuana to cope with the pain." It was also noted "patient describes feelings of guilt saying he isn't there for his siblings the way his father was there for him."
Lamoureux said this shows that it appears Josh hadn't processed the trauma of the murders.
"Josh was consumed with becoming a strong young man. You see it in the texts with (his mother)," said Lamoureux. "He wanted to be a rock for the people he loved. That was his purpose in life."
Less than half a year after the murders, Josh had moments "he realized he needed to check himself," Lamoureux said. "That's not consistent with someone who was yet suffering psychotic paranoia."
Lamoureux said his diagnosis of Josh's mental state would have been PTSD resulting in depression and extreme anxiety from the trauma caused by the murders.
"Josh wasn't in full-blown psychosis," Lamoureux said.
Lamoureux told the jury the Ben Taub records are the "most critical" to the analysis of Josh's mental state because that hospital stay occurred closest to when the murders happened.
As the months passed, Josh's mental health appeared to decline. Nearly two years after he sought help at Ben Taub, medical records from Pearland Psychiatry paint a grim picture.
"He is now moving into paranoia, psychotic realms," Lamoureux said.
Details about Josh hallucinating, neglecting his hygiene, and having thoughts of killing people, specifically about a "woman in his head he wants to hurt," are detailed in the hospital records. At one point, it's noted Josh set a towel on fire and put it in the oven because he tried to "freshen the house."
"This person's thinking is disorganized and illogical. There is no homicidal intent here," Lamoureux said.
"How is that different from someone who puts gas in a rubbing alcohol bottle and tries to set the house on fire?" Jordan asked.
Jordan was referencing the fire prosecutors say A.J. started outside his parents' bedroom 48 hours before the murders. During his police interrogation, Armstrong told officers it was an accident. Dawn had texted Josh about the incident saying she caught A.J. "try(ing) to set the house on fire," calling him a "liar."
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"That's pretty clear homicidal intent," Lamoureux said on the stand. "The fire would cut off the exit."
For hours, prosecutors read excerpts showing Josh's mental health demise. There were records of him attacking family members, "snarling" at medical staff, and, at one point, refusing to speak to doctors.
About 18 months after the murders, one record stated: "Patient experienced watching the murder of his parents in 2016."
Lamoureux said, at the time, it was clear this sentiment was "taken from a third party because Josh himself was not responding to questions."
"A lot of his paranoia could be associated with guilt," Collings said while questioning Lamoureux.
As a trained forensic psychiatrist, the doctor also weighed in on the Armstrong crime scene, saying it doesn't show signs of a killer who would have been under psychosis.
"Psychotic crime scenes are often messy, gory, disorganized," he said. Leaving the murder weapon on the kitchen counter, writing a note, and pulling out drawers "looks like a thoughtful progression of actions," Lamoureux told the jury.
Based on his expertise, he said the crime scene appeared "unsophisticated," noing someone who has psychosis would not return to the scene. Josh went to his parent's house minutes after A.J. called him.
"Twenty-two months later, the story of Josh trying to make his way in the world that's a lost dream. Now we've moved into a person of psychotic schizophrenia," Lamoureux said. "It's unlikely he'll ever have a normal life."
Lamoureux was the state's 26th witness to testify and the only witness to testify today.
On Friday, the state is expected to rest its case.
Courtney Fischer is bringing all the latest updates on AJ Armstrong's third murder trial on Facebook, Twitter and Instagram.