BRAMPTON, Ont. - The credibility of an informant in the so-called Toronto 18 case came under attack Thursday as the lawyer for an alleged terror leader tried to paint Mubin Shaikh as a drug abuser who gave selective reports to police.

Shaikh is the Crown's key witness at the trial of Fahim Ahmad, Steven Chand and Asad Ansari, who are charged with terrorism offences.

During a second day of cross-examination Ahmad's lawyer, Dennis Edney, grilled Shaikh about his drug use.

Shaikh, who had a slight smirk on his face during Edney's most intense questioning, said he began using cocaine, doing a "couple of lines," in late May 2006. Then over the next few months he became addicted, needing another fix as frequently as every 20 minutes, he said.

"It was out of control," Shaikh told the jury trial.

"By December of 2006... you were now an addict and a father of five children, and someone whose evidence we're relying upon in the course of this trial, yes?" Edney said.

Shaikh agreed, but noted that his first hit of cocaine came mere days before a group of men and youth were rounded up on June 2, 2006 and charged with terrorism offences. The investigation and the subsequent attention were traumatic events that precipitated his addiction, he added.

Shaikh has testified he worked with CSIS on the investigation since 2004, later became an RCMP agent and attended a terrorist training camp north of Toronto in December 2005 allegedly led by Ahmad.

He gave an interview to the CBC in July 2006, revealing his identity and his role in the investigation. In court Wednesday he said he went public in part because he was disappointed the RCMP had not publicly recognized that some in the Muslim community had helped the investigation. However, he said he had a hard time dealing with the results of the interview.

"You have no idea the fallout that occurred in the community thereafter," Shaikh said. "I became very depressed because of what happened."

Shaikh said he told his RCMP handlers he was addicted to cocaine in December 2006 and they sent him to counselling. His drug use continued for several more months, until he decided that his recovery required a religious element, Shaikh said, adding he got clean on a pilgrimage to Mecca.

The Crown alleges Ahmad was the leader of a terror cell and held two training camps to assess his recruits' suitability to help carry out his plans to attack Parliament, electrical grids and nuclear stations.

The first time Shaikh met Ahmad was Nov. 27, 2005, at a banquet hall and Edney suggested Shaikh purposely omitted telling his handlers comments from a few other people in attendance who spoke well of Ahmad.

"Did you report to your handlers the good things that you heard about Fahim that night?" Edney asked.

"I chose more to believe what I observed directly," Shaikh said. "Short answer: no."

"So when you pick and choose what information to pass along, what is the basis for that?" Edney asked.

Shaikh replied that he didn't think the opinions of those people held much weight, and disagreed with Edney's characterization that the information Shaikh gave to police after that night was a biased view of Ahmad.

"I don't think I've ever given a one-sided appraisal," Shaikh said, noting he told police he though Ahmad was a good Muslim, for the most part.

Edney suggested that the comments Shaikh reported Ahmad as making did not add up to extremist views or anything that should have led him to tell police Ahmad was a danger to Canada.

"So far what I've heard is that he complained about the treatment of Muslims abroad, which you agreed with," Edney said. "So is there anything else I've missed out?"

"Yes, everything else I said," Shaikh replied, saying Ahmad suggested something should be done about that, including attacking targets in Canada.

Ahmad, 25, Ansari, 25, and Chand, 29, are charged with participating in a terrorist group. Ahmad is also charged with instructing people to carry out activities for a terrorist group and a weapons offence. Chand also faces a charge of counselling to commit fraud over $5,000 for the benefit of a terrorist group.