Returning to the stand in his own defence, Ron Cyr says he believes it was his close friend Zdenek 'Dennis' Zvolensky who killed his wife, Nadia Gehl.

Zvolensky, Cyr and Nashat Qahwash are each charged with first degree murder in the February 2009 shooting death.

Cyr told the court on Tuesday that in 2008 Zvolensky had been pushing him to be part of purchasing a business called ‘Canoeing the Grand.'

It would have been a partnership between Cyr, Zvolensky and Qahwash, but Cyr says while he thought it was a good idea he told Zvolensky he wasn't interested and didn't have money to invest.

He says Zvolensky believed the business was his way to a new life and on Dec. 12, 2008, two months before the killing, it came to a head when Zvolensky pressed him on why he wasn't interested.

Cyr says he told Zvolensky he wasn't the one that didn't want to do it, but that his wife wouldn't let him because she didn't trust Zvolensky.

Cyr said he believes "That was the moment I killed Nadia."

Four days after Gehl was killed, Cyr says he was confronted by Zvolensky at a Kitchener community centre where all three of the accused worked.

He says Zvolensky had the gun, told him to shut up and not say a word.

According to Cyr, Zvolensky then told him he had killed Gehl in the most public way possible as she was part of the ruling elite holding him down and that he could plant the gun and implicate Cyr.

Cyr says Zvolensky told him he was going into the business and would finance it, that it wasn't personal, it was business.

Zvolensky allegedly also told Cyr he waited for Gehl as she left home to walk to a bus stop, with Qahwash acting as his lookout, and then executed the killing with military precision.

An alibi and an affair

Also on the stand on Tuesday, Cyr admitted he had been having an affair with Michelle Brown.

Brown was a clerk at the Gehl and Gehl law firm, run by Nadia's father and uncle, where Cyr worked as a legal assistant.

Cyr says the affair went on before and after he was married in June 2008.

He also testified he was at the courthouse in Cambridge the morning his wife was murdered, and he only found out after he went to the scene and was told by police.