SAINT-JEROME - After four days of explaining in his own words what was going on inside his brain when he killed his children, some inconsistencies emerged in Guy Turcotte's story when the Crown's cross-examination began Friday at his double murder trial.

Over those four days, Turcotte said his motivation for killing his son Olivier, 5, and daughter Anne-Sophie, 3, in February of 2009 was so that they would not have to deal with the pain of his own suicide.

However, the Crown is attempting to prove that Turcotte in fact was attempting to get back at his estranged wife Isabelle Gaston, who had begun seeing another man.

Prosecutor Claudia Charbonneau asked Turcotte many questions Friday regarding the suicidal thoughts Turcotte had described in such detail all week, dating back two years prior to the killings.

She wondered why the 39-year-old cardiologist never attempted to access the powerful drugs available at the Hôtel Dieu Hospital in Saint-Jerome where he worked rather than his chosen method of ingesting methanol.

"The medications are at the hospital," Turcotte answered, "and I'm never suicidal at work."

Methanol is known to take up to 36 hours to kill an adult, but Turcotte said he believed he would fall into a coma and die within 24 hours.

Charbonneau countered by showing the results of some of Turcotte's own Internet searches on methanol that showed the liquid to be a very slow killer.

Charbonneau also challenged Turcotte's claims of the depths of his own insecurities and the efforts he says he took to remedy his personal problems.

Turcotte often visited with a life coach, but never told him he was suicidal in the weeks leading up the tragedy. Also, earlier this week Turcotte said he was worried about disappointing his deeply religious family, yet he now admits he's been an atheist since his teens.

The court adjourned at midday and Turcotte's cross-examination will continue Monday.