Prosecutors cross-examining a London, Ont., doctor accused of joining a terrorist cell in Ottawa are attempting to cast doubt on his claims he stumbled upon a pre-existing conspiracy and was just pretending to be interested in participating.

Khurram Sher

Khurram Sher, right, is facing a charge of conspiring to knowingly facilitate a terrorist activity. (CBC)

Dr. Khurram Sher is charged with conspiring to knowingly facilitate a terrorist activity. A former pathologist who lived in London, Ont., Sher also once appeared briefly as a contestant on Canadian Idol.

In two days of testimony in front of an Ontario Superior Court judge, Sher spent most of his time going through wiretap transcripts with his defence lawyer, Michael Edelson.

The transcripts cover a conversation between Sher and two other men during a late-night meeting at an Ottawa townhouse on July 20, 2010.

That meeting forms the crux of the case against Sher.

3 taped discussing attack on CFB Trenton

According to the wiretap transcripts, the three discuss sending money to the Taliban, travelling to Pakistan to get military training, forming a group and electing a leader from among the three of them.

They also talk briefly about bomb making, and appear to discuss a potential target: CFB Trenton in Ontario, the base where the bodies of Canadian soldiers killed in Afghanistan are repatriated.

In testimony earlier this week and on Thursday, Dr. Sher told the court that he never expected to find himself in such a conversation. He said he was surprised that one of his alleged co-conspirators, an old friend, was involved in such an affair. He said he had never met the other man prior to the meeting, and never met him again afterwards.

Sher testified that despite several incriminating statements he made during the conversation, he was merely playing along and pretending to be interested in participating in jihad with the other two men. He said he wanted to understand how serious the other two really were, and that he was lying when he told them he had made contact with a Taliban member during a recent visit to Pakistan.

But prosecutors cast doubt on Sher's claims of non-involvement.

In cross-examination crown attorney Jason Wakely reminded Sher about emails where he appeared to disparage non-Muslims and refer to them as "kuffar" or "infidels", suggesting that he was not the apolitical hockey fan he sought to portray himself as.