An undercover police officer testified he “groomed” accused murderer Joseph “David” Caissie to talk about the death of Carol King, but that the goal was to get the truth about the murder, regardless who did it.

The officer spent much of Thursday on the stand being cross-examined by defence lawyer Kevin Hill during a voir dire at Saskatoon Court of Queen’s Bench. Justice Richard Danyliuk will determine if all evidence heard in the voir dire, including a confession from Caissie in a Mr. Big sting, will be admissible in trial.

Mr. Big stings are an undercover operation by police that sees officers bring a suspect into a fake crime ring to get answers about a case that’s often gone cold.

Caissie is charged with first-degree murder in the 2011 death of King and was arrested in 2016, after the months-long Mr. Big sting.

“We portrayed ourselves as criminals,” the undercover officer, whose identity is protected under a publication ban, said on the stand.

“But to him it’s reality,” defence lawyer Hill said.

Hill argued Caissie was made to believe the murder made him an asset to the fake criminal organization because he could “take care of business.”

“That’s encouraging him for having killed someone. Praising him,” Hill said.

The officer on the stand disagreed, saying it’s letting Caissie know he was OK with murder.

“The underlying tone of the major crime technique ... is about discovering the truth,” the officer testified. “In order for us to do that, a lot of what my character would be doing in these sorts of situations, is trying to give the impression that in a way I’m not really overly concerned about it.”

He said he groomed Caissie to be comfortable to talk about the murder of King without planting doubts in his mind that the officers are police.

“People are wondering if we’re the police,” the officer said. “And at the end of the day when they take the leap of faith, they’re hoping it’s real.”

Hill pointed out that Caissie’s confession included information about physical evidence that was already known to the public at the time, but a small detail about how many windows were rolled down on King’s PT Cruiser when it was found did not match.

King, 40, disappeared on Aug. 6, 2011 near Herschel, Sask. Her car was found days later in a slough east of her home, and later that month her remains were found a few kilometres from where her PT Cruiser was recovered.

Caissie is heard in audio recordings from the sting telling officers he grabbed King from her home and tied her up before driving her to a treed area and stabbing her once in the chest. He said there was little blood and disposed of her body in a treed area before driving her vehicle into water.

The officer said he didn’t recover the knife Caissie said he threw away in the area after the murder.