Tapia is charged with shooting his upstairs neighbors on Dec. 20, 2013. An elderly man was killed and his wife was injured.
Tapia's attorney, William Paparian, said it's a tragedy that "should have been prevented." Paparian and Tapia's fiancée spoke at a news conference Monday, detailing Tapia's mental state.
"A sudden, abrupt, loud thump coming from upstairs sparked an equally sudden, abrupt mental breakdown from my fiancé," said Tapia's fiancée Elizabeth Valdez.
Tapia's attorney says the VA hospital did little to help his client's PTSD.
"Instead of pushing pills at him, which is what they did, they should have provided the treatment that we know is available for persons that suffer from traumatic brain injury," said Paparian.
They say Tapia was in combat in the Second Battle of Fallujah, one of the fiercest battles in Iraq, and was knocked out in an explosion.
After his discharge in 2010, he wrote these statement in a claim for benefits: "Wake up sweating...nightmares of in combat...get irritated easily and outbursts of anger...I have also witnessed graphic death scenes...I smelt bodies for a whole week after our attack through Fallujah."
Two weeks before the shooting, Tapia was placed on a psychiatric hold at the VA hospital. He was released one day later.
"He's hallucinating still -- both auditory and visual hallucinations. He sees the insurgents in Fallujah coming at him and he hears their voices," said Paparian.
Valdez said Marines receive intensive training to prepare them for combat but there is no boot camp for their transition back to civilian life.
On Wednesday, Tapia's attorney will be in court asking a judge for a psychiatric evaluation of his client.
Eyewitness News sent emails and left messages for the VA on Monday, but so far, no one has gotten back to us. We also tried to find the surviving victim of this shooting at the Reseda apartment building, but we were told she has moved out of the area.