Some are asking about what warning signs 42-year-old Scott Dekraai may have shown, and what was going on in his life that could have prompted that much rage and anger.
Psychologists note in child custody cases, when a parent doesn't get what he or she wants, they often feel their parenting is being attacked. This can bring on a deep, different kind of rage. And in these cases, parents dueling for custody become so adversarial they forget what's best for the child.
Court records also tell us more about the mental state of Dekraai. A 2007 tug boat accident left him with painful leg injury and a diagnosis of post traumatic stress disorder. Experts say he also had depression and severe anxiety.
Some experts believe it was this type of slow building rage combined with several other factors that may have lead to Wednesday's massacre.
"You add to that the other side, which is the custody dispute, the anger, the rage, and the acrimony between him and his wife, and you have to what amounted to unfortunately a perfect storm," said Dr. Nadim Karim.
Karim is a forensic psychologist and PTSD expert who often testifies in child custody cases. He says witness accounts of how Dekraai would show up at his wife's salon in the past and have heated arguments were clear warning signs.
"What we can learn is the fact that we need to be more vigilant when we experience violence, or violent behavior, or in this case angry and rageful episodes within the workplace," said Karim.
Dekraai's neighbors in his Huntington Beach neighborhood painted a different picture. They described him as a kind, doting father.
"He seemed like a very loving man, open to the neighbors," said one neighbor.
It's a description Karim says is consistent with people suffering from depression and PTSD.
"So many times it's not surprising to hear that he may have put up a good front with his friends and neighbors in that regard," said Karim.
Karim says people with PTSD can often start acting irrationally. And it was the combination of stressors and an escalation of anger that may have put Dekraai over the edge.
"He didn't just go after his ex-wife," said Karim. "He went after individuals that were innocent bystanders and began randomly shooting them for absolutely no reason whatsoever."
There is still a lot of speculation as to what was going on Dekraai's mind. And another question that remains is whether or not he was getting any treatment or counseling.
Karim says that therapy is one thing that could have possibly helped Dekraai deal with his ongoing custody battle and the struggles he faced.