As the trial continues, jurors will also consider whether the suspected shooter's parents are responsible.
The suspect, Dimitrios Pagourtzis, is being held in a mental facility after being found incompetent to stand trial for the May 2018 massacre.
The trial comes after the mayor of Santa Fe called on the Justice Department to investigate the massacre at the high school.
On Wednesday, the attorney for the victims showed gun cases he says Pagourtzis, the accused shooter, raided. Jurors saw photos of bomb-making materials and even a shirt he allegedly wore on the day of the shooting with the words "Born to Kill" on it.
"I'm sick and tired that every time a school shooting happens, it's always, 'Thoughts and Prayers,' and that (doesn't work anymore)," Rosie Yanas, the mother of victim Chris Stone, said.
"He wanted to wrong others to avenge the perceived wrongs that had been done to him," Clint McGuire, the lead plaintiff attorney, said. "This was not a snap decision."
The question is whether Pagourtzis and his parents are financially responsible for those killed and injured. A lawsuit filed by survivors and victims' families claims his parents were negligent by allowing him access to guns and failing to get him mental health treatment.
In a motion filed by Pagourtzis' parents last week, they said they do not have a duty to control the conduct of others and that the injury to the plaintiffs was caused only by their son.
Since Pagourtzis was found incompetent, an attorney has been appointed to communicate with the court on his behalf.
"Don't lay the hammer on the one person that was crying out for help and was left helpless," Roberto Torres, Pagourtzis' ad Litem attorney, said.
While in court, Pagourtzis' mother appeared to get emotional multiple times.
"Are they at fault because they didn't know what they didn't know? I don't think so. This could happen to any parent," Lori Laird, who is representing Pagourtzis' parents, said.
"I don't like to hear excuses. There's no excuse for murder," Yanas added. "You can't give me an excuse and tell me it's because of this that my son is dead."
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SEE MORE:
- Santa Fe shooting suspect's mental state has 'degraded': attorneys
- Judge decides to move Santa Fe HS shooting trial
- Dimitrios Pagourtzis: What we know about the Santa Fe shooting suspect
- Bomb technicians surround home near Santa Fe High School following deadly shooting
- 10 dead, 13 injured in shooting at Santa Fe High School
- Survivors and victims' families attend emotional hearing as suspected Santa Fe HS shooter appears in court
- Dimitrios Pagourtzis doesn't remember many details of shooting at Santa Fe High School, attorneys say
- Timeline: How the deadly shooting at Santa Fe High School unfolded