VANCOUVER - A British Columbia judge has told jurors they will have to decide whether a man who confessed to killing a 12-year-old girl could have obtained details about the crime from police or media reports.

B.C. Supreme Court Justice Austin Cullen is instructing a jury that is expected to start deliberations later Monday in the trial of Garry Handlen, who confessed to the 1978 murder during a police undercover operation.

Monica Jack was last seen in Merritt while riding her bike and her remains were discovered in the area 17 years later.

Handlen became the subject of a so-called Mr. Big sting in Minden, Ont., in early 2014 and provided an alleged confession recorded on a hidden camera that was shown to the jury during the first-degree murder trial that began in October.

Defence lawyer Patrick Angly has argued Handlen was provided information about the crime by the RCMP in 1978 when he was interviewed and also by a supposed crime boss asking leading questions in November 1994.

In the video, the boss of a fictitious criminal organization is seen shuffling through some papers, including a printout of a newspaper article that includes a photo of Jack, while he and Handlen are seated on a couch in a hotel room, where the man allegedly confessed to killing the girl.

Angly has said it was possible for his client to have read some information about her murder in the article and then parrot it back to the boss in the form of a confession, which he maintains is false.

The lawyer also told the trial Handlen may have gleaned details about Jack's murder from a television documentary and his coerced confession did not include any new information that would have been known only to the killer.

In the confession, Handlen said he grabbed Jack from a highway pullout, threw her bike into Nicola Lake, put her in the bathroom of his camper and drove up a hill, where he sexually assaulted and strangled her before burning her clothes and part of her body.

“All I can tell you is what I know for sure is I went up a dirt road off the highway, up a hill, somewhere in the Merritt area and I left her body up there,” Handlen says.

The judge has told jurors the cause of Jack's death has never been verified.

The Crown has maintained Handlen agreed to go on a two-day trip to the Merritt area with other undercover police officers and pointed out one of 17 pullouts where he thought he snatched the girl.

Before his confession, Handlen is told that along with the DNA, witnesses have placed him at the scene of the crime.

The boss says Handlen will have to accompany other members of the group to point out the spot where he abducted Jack so a former employee has enough information to take the blame.

Handlen says he's concerned about being seen in the area, which the Crown maintains weighs against him.

“They're not going to see you,” the boss says in the video. “We'll look after that, don't worry. We'll get you into something that's got nice tinted windows.”

Handlen then agrees to go, saying: “I have to get out there somehow and show somebody.”

Another undercover officer told court Handlen became visibly upset and distraught during a re-enactment of where he said he grabbed Jack.

“It seems to me either way that would create stress in a person,” Cullen told jurors Monday.

The RCMP set up 81 elaborate scenarios with Handlen, who thought he'd been recruited by a criminal gang that paid him almost $12,000 for jobs such as selling counterfeit goods.