Three current and former Calgary police officers engaged in a two-year "campaign of harassment" against a Calgary mother with the goal of getting her to give up her parental rights during a bitter custody battle, according to the prosecution at the start of a four-week corruption trial.

Tony Braile, Bryan Morton and Bradford McNish were paid thousands of dollars by a private investigation firm to illegally use Calgary Police Service resources, said Leah Boyd, who is prosecuting the case alongside Julie Snowdon.

The trio face charges of bribery and unauthorized use of a computer system. Braile and Morton also face charges of criminal harassment, while Morton and McNish each face a charge of breach of trust.

All alleged offences stem from activity between 2012 and 2015 during which time all three were CPS officers, though Braile had been suspended for unrelated matters.

Court heard Monday the trio was working for a private investigation firm run by retired CPS officer Steve Walton and his wife Heather, a retired civilian employee of the service. The PI firm had a client named Ken Carter, who was in the middle of an acrimonious split from his partner, Akele Taylor.

The charges stem from a "protracted and acrimonious" custody battle between Taylor and Carter during which the prosecution alleges Taylor was stalked and harassed by employees of the PI firm.

The goal of the three on trial — according to the testimony of Det. Todd Nichol of CPS's anti-corruption unit — was to pressure Taylor to give up her parental rights by gathering information that was designed to show she was an unfit mother.

Braile even pretended to be interested in purchasing Taylor's home so he could install "listening devices," said Nichol, who eventually became the lead detective for the investigation.

The Waltons and Carter face similar charges related to the corruption investigation and are set to go on trial later this year.

'All three were very well paid'

The Waltons are alleged to have paid the three men on trial to provide "extensive, overt surveillance of Taylor for many months," which included a GPS device being covertly attached to her vehicle.

Beyond the surveillance, Taylor's friends and family were offered money to say negative things about her, according to Boyd, who said the woman was a victim of "stalking-type activity."

"All three were very well paid by Mr Walton," said Boyd. McNish was paid thousands of dollars while Braile and Morton received tens of thousands in compensation.

Evidence gathered by running checks through CPS information systems — which were done while the accused officers were on duty — were worth up to $1,000 per inquiry, said Boyd, who also alleges Morton used police vehicles to follow Taylor.

Braile's statement

The trial began with a voir dire — a hearing to determine the admissibility of some of the Crown's evidence, which in this case includes a document that Braile's lawyer claims is protected by solicitor/client privilege.

In 2015 or 2016, Taylor hired lawyers Francisco Torres and Clive Llewellyn to sue CPS. In preparing for that lawsuit, Torres had Braile "share his story" in a sworn affidavit about what happened to Taylor.

At the time, Torres said he would not use the document without Braile's permission.

"I never foresaw this situation," said Torres, who admitted he didn't warn Braile the affidavit could be used against him in criminal proceedings.

A decision won't be made on the admissibility of Braile's statement until Torres and Llewellyn finish testifying at a later date.

Braile was fired by CPS in 2016 for professional misconduct relating to a 2008 high-speed chase. He is appealing the service's decision.

Last month, Morton — who is currently suspended from CPS — was charged with assault stemming from an incident that took place while he was working as a bouncer in Halifax.

The trial is set to last four weeks. Court of Queen's Bench Justice Bryan Mahoney is presiding over the judge-alone trial.

Senior defence lawyers Pat Fagan, Jim Lutz and Paul Brunnen represent Braile, Morton and McNish, respectively.