A former pastor accused of drugging and drowning his pregnant wife in a bathtub has been found guilty of manslaughter by a jury.

Philip Grandine, 28, accidentally described by his lawyer during closing arguments as "Mr. Lorazepam," remained impassive as the verdict was read.

After a brief two-week trial in a downtown Toronto courthouse, the jury deliberated for about 21 hours, starting at 3:35 p.m. Tuesday.

Grandine was charged with first-degree murder six months after his wife died on Oct. 17, 2011.

Anna Karissa Grandine was 29-years-old and 20 weeks pregnant when she died.

She never learned the sex of the baby — she died four days before that doctor's appointment, the trial heard.

Karissa, as she was known to friends and family, was excited about the child and becoming a mother, Crown prosecutor Donna Kellway told the jury in her closing statement.

On her bedside table, by a pillow that became stained with vomit on the night of her death as she reacted to the sedatives, was a pregnancy book.

The defence argued that Karissa took her own life, on purpose or by accident, in a fog of depression brought on by her husband's infidelity which she learned about in August 2011.

Grandine resigned as a pastor at the Ennerdale Baptist Church after his affair was discovered, standing up before the community and admitting that he had cheated on his wife with a parishioner.

The couple began marriage counselling and a computer filter to prevent him from watching pornography was installed on their home computer. It was uninstalled on the night Karissa died.

The Crown argued that Grandine killed his wife so he could be with his mistress Eileen Florentino. He had told her three times that he wanted to run away with her, Kellway said.

He told his family doctor that if he could do things over again, his "stubborn" wife Karissa would not be his first choice.

As a trained nurse working as a manager at a retirement home, Grandine had access to sedatives like Lorazepam, Kellway told the jury.

He used the home computer to do Internet searches on how much of the drug would be fatal. Search terms included: "autopsy," "Lorazepam" and "overdose," indicating that he was concerned about the death looking suspicious, Kellway argued.

That's why he used a high but still "therapeutic" dose of the drug, so it would not look like an overdose, Kellway said.

He first used himself as a guinea pig to test the effects of the drug, making him drowsy and nauseous, the Crown argued.

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Then he conducted a "dress rehearsal" for the murder, spiking Karissa's banana smoothie with the sedatives. Four days before she died, Karissa was hospitalized and told her friend that it felt like she "lost a day of her life" because she could not remember what had happened. She wondered to her sister whether Grandine had put something in her drink. Her mother testified that Karissa asked Grandine the same question at the hospital. That night, though Karissa asked him to stay with her at the hospital according to her mother, Grandine went to see Florentino.

On the night of Oct. 17, 2011, a Monday, the Crown said that Grandine put the final plan in motion. He once again drugged Karissa's smoothie and either carried or coaxed his disoriented or possibly unconscious wife to the bathtub, Kellway said.

He may have gently held her head under the water, or simply let her body sink, Kellway said. Then he called 911 from the landline in the Scarborough home.

The 911 call, the defence argued, shows Grandine genuinely tried to help his dying wife when he found her in the tub, her head by the tap end of the bath, after coming home from a night time jog.

He actually spent much of the jog on the phone with Florentino, their final call ending three minutes before he dialed 911, the court heard.

The Crown questioned why Grandine, as a nurse, did not immediately begin CPR, drain the tub, or try and remove Karissa's body. Kellway suggested that there was no evidence Grandine ever performed CPR on his wife — he may have been faking to convince the 911 operator. In a later interview with police, Grandine said he felt "helpless."

Superior Court Justice Robert Clark specifically warned the jury not to punish Grandine for behaviour they may find "morally repugnant." He is on trial for murder, not "any moral failings you may attribute to him," Clark said in his charge to the jury.

The jury had the option to convict Grandine of first-degree murder, second-degree murder or manslaughter, or acquit him.

In a question to the judge on Wednesday the jury asked: If Grandine had knowledge of Karissa taking a bath while under the influence of the sedatives and didn't stop her, is that the same as causing her to get into the tub?

Clark responded that Grandine has a legal duty to protect his spouse from harm and explained that failing to stop her from taking a bath while under the effects of the drug could constitute an unlawful act.