Photo: CTV News Kathryn-Mary Herbert is shown in an undated family handout photo during a press conference in Vancouver on March 8, 2012.

The man convicted last month of murdering 12-year-old Monica Jack in 1978 outside Merritt told police he also killed another young girl, but that confession never made it to trial.

Garry Handlen, 71, was arrested in 2014 and charged with two counts of first-degree murder in the deaths of Monica Jack and 11-year-old Kathryn-Mary Herbert, who went missing in 1975 near Abbotsford.

During an elaborate 10-month “Mr. Big” operation, Handlen told undercover officers posing as gang members that he had killed Jack in the hopes they would be able help cover up the crime.

The undercover agents told Handlen police already had DNA evidence and were closing in on him, but the gang may be able to convince another cancer-stricken member to confess to the crime for a price.

Two days later, he also told undercover officers he killed Kathryn-Mary Herbert. He showed the officers the approximate area he abducted Herbert and dumped her body, both areas that were close to the area where her body was found.

But because the confessions were made during a so-called “Mr. Big” operation, they were deemed presumptively inadmissible, forcing the Crown to argue at a pre-trial hearing that the “probative value of the evidence exceeds its prejudicial effect.”

In a decision handed down last summer but published online this week, Justice Austin Cullen allowed the confession of the Jack murder to proceed to trial but ruled the Herbert confession inadmissible.

Cullen noted that the Crown’s own evidence showed that Handlen had the tendency to tell “tall tales.”

“The accused had a propensity to lie in the course of dealing with his cohorts, to make up stories and to exaggerate or embellish incidents,” he wrote.

During the pre-trial hearing, Handlen denied the murders and claimed he learned the details of the Herbert case from media reports and documentaries. Handlen had a long and violent criminal record with multiple rape convictions prior to his arrest.

Justice Cullen found that the confession of Jack was admissible, but in essence, tainted the following confession of the Herbert murder.

“At the time when the accused confessed to killing Ms. Herbert, he had already gone out on a limb by confessing to the murder of Ms. Jack,” Cullen wrote. “In doing so, his hope and expectation was that he would achieve a number of things, including ongoing work with the criminal organization with accompanying social and financial benefits, and more importantly, a way out of the dilemma he believed he was facing from the linkage of his DNA to the remains of Ms. Jack.

“Agent A had earlier dismissed the accused’s suggestion in relation to the Herbert Homicide that his DNA could have been planted,” Cullen continued, noting the undercover officers told Handlen “anything short of a confession to the crime would not only end his involvement with the organization, but would, as well, leave him without any hope of avoiding eventual arrest and prosecution for the Jack Homicide.”

The judge’s decision was covered by a publication ban, meaning the jury in the Jack murder trial had no knowledge of it.

Regardless, the jury found him guilty of the Jack murder primarily on the basis of his confession to the undercover officers and he was sentenced to life in prison with no chance of parole for 25 years. The Herbert murder charge was dismissed.