An Ottawa judge has instructed a jury that if former Saskatchewan Mountie Kevin Gregson is to be found guilty of first-degree murder, the jury must decide he knew his plan to take a police officer’s gun would cause bodily harm and that death was a likely result.

Judge Douglas Rutherford began to deliver instructions after the defence and Crown wrapped up their closing arguments on Monday. He will continue tomorrow and told the jury to expect to start deliberating Tuesday morning.

Kevin Gregson, 45, is charged with first-degree murder in the death of Const. Eric Czapnik, 51, who was stabbed outside the Civic Campus of the Ottawa Hospital the early morning of Dec. 29, 2009.

Gregson's testimony

Kevin Gregson described in court Thursday his fatal confrontation with Ottawa police Const. Eric Czapnik. Read the transcript here.

Gregson has pleaded not guilty to first-degree murder, as well as to a charge of robbery in relation to a carjacking the night before the stabbing.

Rutherford told the jury they had to use "human wisdom and common sense" to determine how much of Gregson's testimony was true.

He also said there was "little or no dispute" to the evidence from the defence and a person is presumed to have the capacity of forming intent. The jury must decide whether Gregson has the ability, though.

Rutherford added the jury had no choice but to convict Gregson on the carjacking charge he admitted to.

In his closing arguments Monday afternoon, Crown attorney Brian Holowka accused Gregson of lying about the severity of stab wounds to his own neck, which Gregson had testified were from a suicide attempt.

Holowka also compared Gregson's neck wounds to those on Czapnik, which he called "devastating." He then attacked Gregson's mental health defence, which he said changed to the claim "my training made me do it," because the defence was "untenable."

Holowka told the jury there was no evidence Gregson suffered from any mental health issue.

Defence calls slaying 'wrongful', but disputes intent

In the defence's closing arguments Monday morning, lawyer Craig Fleming conceded many details surrounding the stabbing, including the medical evidence.

"Kevin Gregson committed culpable homicide of Eric Czapnik, and it was wrongful, but there was no intent or plan to murder him," Fleming told the jury.

Fleming argued Gregson had only killed Czapnik after the officer attacked him.

He also called his client "immature" and "selfish." He said Gregson was "stupid" to seek a gun from a police officer and thought he could "take" a police officer because he believed he was tough.

In this case, planning a slaying does not affect a first-degree murder charge. Killing a police officer carries an automatic charge of first-degree murder.

'I killed him, I didn't murder him'

Gregson admitted in court last week to stabbing Czapnik, saying it happened during a fight over Czapnik’s gun. Gregson, who was in the process of being dismissed from the RCMP at the time and was facing allegations of a sexual assault, told the court he was trying to get the gun so he could shoot himself.

"Eric Czapnik, the police officer I killed, he was a good man," Gregson said in the Ottawa courtroom on Thursday.

"I killed him. I didn't murder him," he said.

"This should have been a manslaughter charge, not murder.… I didn't murder him. I waited two years, two months, eight days to tell you that."

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Const. Eric Czapnik died after he was stabbed in the neck on Dec. 29, 2009. (Ottawa Police Service)

Gregson was the sole witness for the defence.

In contrast, Crown lawyers brought forth more than a dozen people to testify, including the paramedics who raced to intervene in the struggle in the hospital parking lot.

Crown lawyers showed video of interviews Gregson had with police — in which he admitted to the carjacking — and physical evidence from the scene, including the two bulletproof vests, two knives, a BB gun and handcuffs Gregson was wearing when he approached Czapnik in his police car.

Gregson's trial was expected to last a month, but the defence rested after only 10 days.

Judge Douglas Rutherford said he expects Monday to be the last day of proceedings before the jury starts deliberating.