WARNING: This story contains details some readers may find disturbing

Strong delusions of having to save her youngest son from hell is what led Kellie Johnson to kill the five-year-old boy, a psychiatrist testified Tuesday.

Dr. Mansfield Mela took the stand at Saskatoon’s Queen’s Bench Court as the defence’s first witness in Johnson’s trial.

Mela specializes in mental disorders in relation to criminal activity. He said the 38-year-old mother’s mental disorder hindered her from understanding the difference between right and wrong when she killed her son, Jonathan Vetter, in January 2014.

Mela assessed Johnson after the death and diagnosed her with paranoid schizophrenia.

Vetter was found dead in a home on the 400 block of Avenue R South. According to an agreed statement of facts in the case, Johnson killed Vetter by slitting his throat.

She pleaded not guilty in February of this year to first-degree murder in her son’s death.

History of mental illness

When Johnson’s trial resumed Tuesday after a more than three-month delay, Mela shared insight in court into her mental health history. Paranoid schizophrenia runs in her family and Johnson had experienced mental health issues for years, he said.

He told court Johnson had been committed — at times voluntarily — to the Irene and Leslie Dube Centre for Mental Health at least three times. She had also been diagnosed with adjustment disorder, obsessive compulsive disorder and paranoid schizophrenia, he said.

Mela testified that in 2006 Johnson began hearing voices and seeing things that didn’t exist.

She believed her boyfriend at the time was sexually abusing her eldest son — though police didn’t find any evidence of abuse.

That’s when Johnson began experiencing psychotic episodes involving an imaginary figure, referred to as “the woman,” according to Mela.

“The woman”

Mela said Johnson told him about “the woman” who would terrorize her and tell her what to do. Johnson obeyed her when she was told to walk outside without shoes for months and stand in the middle of the road.

Delusions of “the woman” became so strong, Johnson believed “the woman” was going to kill her and that Vetter would be in danger, Mela testified. “The woman,” Johnson believed, said Johnson’s ex-boyfriend would raise Vetter and molest him, which would lead Vetter to become a molester himself and send him to hell.

In order to save Vetter from hell, Johnson believed she had to kill the boy in order to send him to heaven first, Mela said.

The killing

Two weeks before Johnson murdered Vetter, she went to Wal-Mart and bought a large kitchen knife. Mela told court her delusions were so strong that she hid the knife from “the woman" so she wouldn’t discover Johnson’s plan and kill her before she could save Vetter.

On Jan. 4, 2014, “the woman” told Johnson she was going to kill her that evening. Johnson hadn’t been taking her prescribed medication for some time and killed Vetter that night. Johnson’s eldest son woke up and saw and heard what was happening.

Mela testified Johnson struggled with killing her son; she knew it was legally wrong, but her mental disorder was so strong it changed her morals.

Johnson truly believed what she was doing was right, Mela said.

Cross-examination

According to the agreed statement of facts, Johnson said, “Oh my gosh, I’m sorry,” after killing Vetter and before running out of the house.

She eventually changed her blood-covered pants in a hospital bathroom, travelled to a different hospital and told a nurse she had a hallucination and may have badly hurt her son.

Crown prosecutor Brian Hendrickson argued Johnson had points of rational thinking. He asked Mela why Johnson apologized if she thought what she was doing was right.

Mela responded by saying, since Johnson knew the killing was wrong by society’s standards, it made sense for her to apologize.

The trial continues Wednesday when court is expected to hear from another doctor who treated Johnson. Hendrickson is expected to call a rebuttal witness — a third doctor who also assessed Johnson.

CTV Saskatoon was in court covering the case. Read our coverage below: