The testimony of an undercover officer who befriended one of the accused, Ronald Cyr, continued in a Hamilton court on Thursday.

The officer, known only as UCJ, is the Crown's key witness in the case. No other details about the officer's identity are being released due to a publication ban.

Cyr, Zdenek ‘Dennis' Zvolensky and Nashat Qahwash are charged with first degree murder in the shooting death of Cyr's wife, Nadia Gehl, in February 2009.

UCJ is slowly taking the court through his day-to-day interactions with Cyr over a five-month period. The officer was initially placed as a furniture salesman at the same store as Cyr.

The officer had an apartment in Guelph wired for audio and video, and his vehicle and cell phone were also tapped for sound. He also often wore a wire.

On Thursday morning he described how their relationship grew quickly through conversations about UCJ's fictitious ex-wife.

The undercover officer described a deteriorating relationship with the ex-wife, which he says Cyr sympathized with.

UCJ also told the court Cyr want to go into business with him, buying the company where Zvolensky and Qahwash worked.

At that point in the relationship, UCJ says he was familiar with all three of the accused, having officially met the other two defendants May 2009

In a recording played for the court Thursday afternoon, Zvolensky is heard telling UCJ he could be trusted to work at the canoeing business the three were planning to purchase.

He said once you've been financially broke you never want to go back to that again and "This and basically you saved by life."

UCJ told the group he had money he was trying to hide from his fictitious ex-wife and was "cleaning it" through his girlfriend's business. (She was also an undercover officer.)

Thus far, UCJ has described his relationship with the defendants from March 2009 up until June 10, 2009, and there are already jokes among the group about killing the undercover officer's so-called ex-wife.

That was meant to lay the ground work for a safe and trusting relationship where the officer could press for more details regarding Cyr's alleged involvement in his wife's murder.

The trial has adjourned until Tuesday when the officer will return to the witness stand.