TORONTO -- A Toronto-area constable under investigation for corruption told an undercover officer he wanted to file an intelligence report about his mistress's alleged involvement in the drug trade after their affair was revealed, his trial heard Tuesday.

The undercover officer, who cannot be identified under a publication ban, is testifying for a second day at the trial of Richard Senior, a longtime constable with York Regional Police.

He told a virtual court Tuesday that roughly two months after he began secretly investigating Senior, the constable mentioned having an extramarital affair with a woman who at one point allegedly sold cocaine, hash and heroin and whose family was allegedly connected to organized crime.

"He told me that he wanted to do an intel report on this girl" to disclose her involvement in the drug business, and talked about how "he was exposed in regards to the cheating," the undercover officer testified.

In an exchange of texts read to the court, the undercover officer told Senior he had some ideas on how he could file such a report and still "insulate" himself from the information.

But the undercover officer testified he never ended up sharing those ideas with the constable.

At another point, Senior expressed concern that the woman would know he was behind the report, the undercover officer testified. The undercover officer asked Senior how many people had the same information, noting that the more there were, the less likely it was to be traced back to him, he said.

Senior has pleaded not guilty to 14 charges, including breach of trust and trafficking cocaine and steroids, in connection with a corruption investigation.

He was arrested in October 2018 and initially charged with 30 offences, but the remaining 16 charges were withdrawn as the trial began.

Prosecutors allege, among other things, that Senior filed an intelligence report about his former flame and falsely attributed it to an informant, who was in fact one of his friends using an alias.

They further allege the officer planned to rob a fictitious drug warehouse after hearing about it from a second undercover officer posing as an informant, and offered to sell the drugs to two men he knew.

In an opening statement earlier this week, the Crown also alleged Senior sold steroids to the undercover officer who is currently testifying and another officer; stole money he was given to pay informants; and inappropriately accessed a police database and disclosed confidential information.

The undercover officer has said he was assigned to investigate Senior for corruption and breach of trust in June 2018, but wasn't told at the time what kind of offences the officer was suspected of.

He testified Tuesday that a supervisor mentioned the possible involvement of steroids in late July.

Part of the undercover officer's objectives was to set up regular workouts with Senior to "continue to build rapport," and he eventually started making inquiries about steroids.

In late July, Senior acknowledged he "used to know some meatheads" who had access to steroids but suggested the undercover officer get on a good diet plan first and take some supplements, court heard.

At one point, the undercover officer asked Senior how much it would cost for a cycle of steroids, and the constable replied, "How should I know?" the undercover officer testified.

In the following days, they exchanged texts about diet plans and supplements, court heard.

At the same time, the undercover officer said he began to engage in "suspicious behaviour" to suggest he also may be involved in criminal activity.

This report by The Canadian Press was first published Jan. 19, 2021.