A Northern California man has been found guilty of the first-degree murder of his ex-girlfriend that took place last year.

Jose Rafael "Rafa" Solano Landaeta, 33, was convicted by a jury on Monday for the murder of his ex-girlfriend and the mother of one of his children, Karina Castro. The 27-year-old mother of two was killed by Landaeta in September of last year after the pair were spotted having an argument outside of Castro's apartment, according to local reports.

In the days leading up to the crime, Castro and Landaeta exchanged a series of angry messages via social media, reported local outlet KRON4. At one point, Castro accused Landaeta of being a pedophile and rapist, a move prosecutors said enraged Landaeta to the point of committing what they called a "vengeance" killing.

Eyewitnesses saw the two having a verbal fight in the street outside the San Carlos apartment, where Castro's two kids were present, on Sept. 8.

They reported seeing Landaeta walk to his car and retrieve what was described as a samurai sword, before returning to commit his grisly act. The witnesses said the murder happened in the middle of the street, with Landaeta "slashing numerous times, causing the victim’s head to be almost severed," according to local source Palo Alto Online.

Castro attempted to flee from Landaeta but was struck at least seven times by the blade, with one witness saying at trial he “saw (Landaeta) swing at Castro with such a blow, her arm was almost severed from her body,” 

He then reportedly returned the bloody sword to his car and soon after surrendered to police when they arrived on the scene, reported KRON4.

Landaeta pleads not guilty

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Landaeta initially submitted a plea of not guilty due to reason of insanity but was later found fit to stand trial by court-appointed doctors. Days before the trial was set to begin, he changed his plea to one of "not guilty," as his defense attorney argued the killing was an act of self-defense and the result of Landaeta's mental health issues.

Defense Attorney Robert Cummings told the jury that Landaeta was diagnosed with schizophrenia and was made to fear for his life because of Castro's messages to him in the days leading up to the murder. Cummings said Castro had threatened Landaeta and his family and showed the jury messages where Castro claimed to have some sort of hit out on her ex.

The stress of these threats caused Landaeta to stop taking his medication, Cummings said, triggering what he argued was a psychotic break. He alleged that Landaeta believed Castro had tried to stab him in the chest with a knife during the Sept. 8 argument, but no knife or evidence of this attack was discovered at the scene.

Landaeta to return for sentencing

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Earlier exchanges between the pair led prosecutors to argue the crime was pre-mediated, as some messages saw Landaeta sending "ninja sword" emojis to Castro. Landaeta likewise went home early from work that day, telling his boss he was sick, and went to his own home to grab the sword and text friends about his plan before driving an hour to Castro's apartment.

"This crime was vicious. This crime was cruel. There is no credible evidence that the defendant suffered from any mental health condition on the day of the crime,” the prosecutor said at trial.

Landaeta, who was absent for multiple parts of his own trial, will be sentenced at a later date and is facing 25 years to life in prison.

Martin Castro, the father of the victim, said he believed his daughter to be a hero who protected her children that day by preventing Landaeta from entering the apartment where her kids were.

“There’s no telling what could have happened if she had been in the apartment and he went up there. She kept him outside and away from (her children),” Martin Castro told KRON4. “She’s going to be my angel for the rest of my life on my shoulder.”