Kevin Rubletz was not yet a suspect in his former girlfriend's disappearance when he sat at a dining room table with three Calgary police officers and painted her as a party girl who may have simply gone on a days-long drinking binge.

Based on information that Rubletz was the last person to see Jessica Newman, missing persons investigator Sgt. Matt Baker had arranged to meet with him at his girlfriend's home in Woodbine on March 14, 2015. 

"He was very calm, polite," Baker testified Tuesday. "Willing to give a statement."

The audio recording of that first police interview was played for jurors on Day 6 of Rubletz's second-degree murder trial. 

In a second police interview two days later, jurors heard Rubletz's story had changed. He added a detail: the night she disappeared, he had driven to the same area where Newman's body would eventually be found two months later.

On the first recording, the former couple's son can be heard in the background as police officers question the boy's father about his final interaction with Newman. 

Rubletz was the last person to see his on-again, off-again girlfriend on March 10, 2015. He said he picked her up from work and had taken her for a coffee around 9 p.m. The pair talked about their court hearing set for the following day when Newman was planning to apply for 50 per cent custody of the son they shared.

Rubletz, 33, told Baker he then dropped her at home about 30 minutes later before driving to his own house.

When the young mother failed to show up at court, Rubletz told police he texted her "where the hell are you?" but received no reply. He told Baker he hadn't worried about her because he thought she might be on a bender. 

"I figured she might have just gone out drinking," Rubletz told the officers. "She doesn't remember what she does, she flirts."

Rubletz's van found in scrap yard

Newman's body was found in a rural ditch north of the city two months after she disappeared. She'd been stabbed 75 times. Jurors heard evidence that her DNA was found in Rubletz's van, where the evidence will show a "bloodletting event" took place.

Last week, jurors saw affectionate text messages exchanged between the two in the months, weeks and days before her disappearance.

According to the prosecution's theory, Newman's death was a "crime of passion" that took place the night of March 10, 2015. Prosecutors Shane Parker and Tom Spark say evidence will show Rubletz killed Newman in his van and then dumped her body north of Calgary.

After Newman's body was discovered in May 2015 in a ditch near Balzac, Rubletz's grandmother, mother and stepfather took the van to a scrap yard, but police were able to intercept it and run tests, jurors have heard.

Rubletz van

The van driven by Kevin Rubletz was found at a pick-and-pull lot after Jessica Newman's body was discovered two months after she disappeared. (Court exhibit )

Two days after the accused gave his first statement to police, he made a "significant addition to his story," said Parker. 

Baker asked what route Rubletz took after dropping Newman at her home the night she was last seen.

Rubletz "hesitated," said Baker. He then told the officer that after hugging Newman and kissing her on the cheek when dropping her off, he decided to go for a drive "to clear his head."

He said he drove out to Balzac. Baker then had the accused retrace the route he had taken that night. 

Under cross-examination, defence lawyer Brendan Miller suggested Rubletz didn't initially tell police about kissing Newman and wanting to get back together with her because he was at his girlfriend's house during the first interview. 

Baker also said in cross-examination that police used an investigative technique on Rubletz called a "stim," where information is released to the suspect in an effort to prompt a reaction that may lead to evidence. 

The investigator said he called Rubletz and suggested police may have found Newman's body. The suspect began to cry and "responded with shock and sadness," Baker confirmed to Miller.

A surveillance kept an eye on Rubletz after that but only observed him taking some garbage outside. Police seized and searched that garbage but found no relevant evidence; no cleaning products, no weapon and no blood.

Rubletz's sister to testify

Baker testified he followed the standard investigative format for missing persons cases checking local hospitals, airports, attempting to track her cellphone and doing banking inquiries. He also followed up on a tip from the public that Newman had been spotted on a C-train. All of his inquiries came up empty.

Baker said the investigation still wasn't criminal when he asked Rubletz's permission to seize his cellphone with the intention of checking its GPS to confirm the route driven the night of Newman's disappearance. Rubletz said he needed it for a few days for work but eventually emailed the officer to say he'd lost his phone. 

The trial is in its second of three weeks and is being presided over by Court of Queen's Bench Justice Glen Poelman.

Rubletz is represented by defence lawyers Brendan Miller and Joshua Sutherland.

On Wednesday, Rubletz's sister is scheduled to testify.