Brian Williams, 24, is accused of killing his mother and sister.
No one saw it coming, according to Howard Williams III. No one could have ever imagined someone would murder his sister Bree, 18, and their mother Donna, 52.
Certainly no one could ever imagine the alleged killer would be Howard's youngest brother, Brian Rockwell Williams, 24.
"He's never been violent, he's never been upset to this degree,"Howard told NBCSanDiego outside the family home in Rancho Penasquitos where the murders took place.
Police sources said Brian suffers from mental illness including schizophrenia and may not have been taking his medications prior to the murders.
Howard didn't want to talk in detail about his brother's mental health.
"There were some periods where he was being a little depressed, but as far as him being mentally ill, I can't comment on that too much,"Howard said.
Howard said he hasn't spoken to his brother since the murders, but plans to visit him in jail.
"I want to find out what happened, I want to find out if he needs any help,"he said.
Howard plans to stand by his brother despite what has happened because he said his parents would want it that way.
"I care for him deeply, love him to death, he's my little brother,"Howard said.
On Wednesday Brian Rockwell Williams will be arraigned for the murders.
Deputies said he is in isolation and refuses to talk to them.