AJ Armstrong retrial: Lawyers set the stage for a murder case against a Houston man accused of killing his parents when he was 16

HOUSTON, TX (KTRK) — At the beginning of the retrial in the AJ Armstrong murder case, prosecutors began their opening statement by bringing a jury into the Armstrong home on that fatal day six years ago when Dawn and Antonio were found murdered in their bedroom. They had each been shot once in the head while they slept in their southwest Houston home.

Looking back on the night of late July 2016, the lawyers focused on the alarm system.

“The alarm went off that night. The doors and windows of this house were locked. The garage was down,” prosecutors told the 15-person jury, which consisted of nine women and six men. “The murder weapon was still in the house and the killer was not a come-and-go intruder. He was in the house the whole time.”

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AJ’s attorneys countered in their opening statements, saying their security experts would show how someone could have gotten into the home without raising the alarm. They also pointed out that they believe there is a lack of evidence in this case.

“No blood on his clothes, no gunshot residue on his shirt, no gunshot residue on his pants and no fingerprints,” defense attorney Rick DeToto said.

DeToto, as expected, pointed the finger at AJ’s older half-brother, Josh Armstrong, as a possible killer. It was a bombshell theory they argued in AJ’s first trial.

“He (Josh) was – and I take no pleasure in saying this – he was absolutely psychotic. Deeply insane and angry. And he was never really investigated,” DeToto said.

WATCH: Watch full video of attorneys on both sides presenting opening statements in Houston courtroom

This time, prosecutors were ready to talk about Josh.

“I assume they (defense attorneys) will ask you to make the jump that he was in the room when he killed his parents,” one of the prosecutors told the jury. “I want you to know that Joshua Armstrong witnessed the death of his parents because he was at the scene when they were being carried on stretchers and loaded into ambulances.”

RELATED: AJ Armstrong’s brother told doctors he witnessed the parents’ murders

Both sides presented the Armstrong family to the jury as the all-American family that had everything: a nice home, nice cars, great vacations, kids in an expensive private school. But the state says life is falling apart, pointing to text messages between AJ and his parents that jurors will see over the next few weeks.

SEE MORE: AJ Armstrong trial: Prosecutors reveal text messages sent before parents were killed

“Honestly, by the end of spring and well into the summer, his parents were at his wit’s end — particularly mother Dawn Armstrong,” prosecutors said.

“Does AJ have problems with his parents?” DeToto countered. “Ladies and gentlemen, how many 16-year-olds don’t have problems with their parents?”

One witness took the stand Tuesday — now Lieutenant JP Horelica with the Houston Police Department. Horelica was one of the first officers to enter the Armstrong home on Palmetto Street. He described a difficult, gory scene in which Dawn and Antonio Armstrong lay in their bed while paramedics tried to save Antonio Sr. He died later in hospital. Dawn was pronounced dead at the house.

WATCH: Full uncut interview with AJ Armstrong

Prosecutors showed several photos of what the inside of the home looked like, as well as photos of AJ and Kaira, AJ’s younger sister, who was 12 at the time, both with their hands cupped, as is the practice when investigators test for gunshot residue.

Horleica’s testimony resumes Tuesday morning at 10:30 am

FAMILY DESTROYED: The AJ Armstrong Murder Trial

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