In an interview with ABC News affiliate KGTV in San Diego, Arlene Holmes described her son as a "happy" and "friendly" child, who would frequently invite friends over to their home. But, things changed around the time he turned 12 or 13-years-old, she said.
"I noticed that he was sadder than a child should be," Holmes told KGTV.
James saw a family therapist for about a year, but he continued to become more quiet, irritable and isolated, and was having trouble "being around people," she said.
Now 28, Holmes said her son showed signs of becoming psychotic by his early twenties. His cognition was declining, he was having trouble thinking and even more difficulty being around people.
He was delusional, Holmes said, with a mentality that he would be "worth more" if he killed people.
"These are the things that people need to really hone in on, and don’t try to do like he did and I did, which is try and just keep going or solve everything yourself," Holmes said. "You need the help of a professional."
Holmes called the mass shooting "horrible" and a "tragedy" that "can't be erased." But, she emphasized that her message is not about James, but for the victims.
"If I don’t deliver this message, I do dishonor the victims, because I think given this opportunity to speak to you, and I need to be brave and take the risk of criticism and go ahead and tell people: this is what he was like," she said.
Holmes said in retrospect, she failed to be educated on the topic of mental health and stressed the importance of recognizing the early signs and symptoms of mental illness.
"I want to offer up the failure as advice to other people," she said.
"I can’t erase the day. But, I wish I could," Holmes said. "And the way that I want to honor their injuries and their distress is to try and prevent something this bad from happening again."