SAINT-JEROME, Que. - The gruesome details of how he killed his own children come to Guy Turcotte in flashes.

Testifying at his murder trial on Thursday, Turcotte remembered in bursts that he stood over the children in their beds, a knife in his hand.

In another, he remembers being in the bathroom, their blood on his hands after he had repeatedly stabbed them to death in a home in Piedmont, north of Montreal.

But what the former cardiologist can't fully explain nearly two years later is why it all came to that in February 2009.

"I'm not able to accept what happened," Turcotte, 39, sobbed as he took the stand for a fourth consecutive day. "I see images (in my head) and I know it happened by my hand, and I'm not able to accept that.

"A father can't do that to his kids. I live with these images that keep coming back to me and I'm terrorized."

In tearful testimony, Turcotte said he'd resolved to end his own life the night of Feb. 20, 2009. He'd even begun drinking windshield washer fluid to that very end.

But at one point it occurred to him that his children — Olivier, 5, and Anne-Sophie, 3 — would wake up to find him dead. So he decided he'd take them with him.

Turcotte, his head bowed, cried during much of his testimony as he explained he was downcast after two intense fights with his estranged wife, Isabelle Gaston.

The couple had split less than a month earlier and she'd taken up with her personal trainer, Martin Huot.

He was feeling down and was crying on the couch while his children watched a video they'd rented. Seeing their father in such a state, each kid in turn got up from the ''Caillou'' video they were watching to console Turcotte.

"Olivier came to see me and took me in his arms and tells me he loves me," Turcotte testified. "I don't know (how I reacted), but Anne-Sophie came to see me too and tells me she loves me."

Once the children had gone through their bedtime routines and were tucked in, Turcotte returned to the computer and started to look at a series of new emails between Gaston and Huot. They had been sent to him a few days earlier by Huot's ex, Patricia Giroux.

He was crushed by the obvious passion in those emails, a love he said he'd never known in his lifetime.

''They love each other, it's evident," Turcotte said of the correspondence.

"Isabelle and myself, we'd never loved each other like that."

He said he felt his life was over. Then he resolved to kill himself and started researching suicide techniques.

"The goal was to die," Turcotte said. "I don't know how to explain it. What I saw (in the email) hurt me and I wasn't able to endure it anymore."

What came after the Internet searches, he said, he could only recall in flashes.

"I can see myself dead, I am dead," Turcotte testified, referring to his condition after after he'd started downing glasses of windshield fluid.

"And I don't want my children to find me dead. I say to myself, 'I'm going to take them with me.'"

In one mental snapshot, he recalls attacking his son.

"I have a knife in my hands, I stabbed him and Olivier told me 'Nooo!'," said a sobbing Turcotte.

"He struggles and I realize I'm hurting him. I panicked and stabbed him some more.''

In another memory, Turcotte was standing in Anne-Sophie's room with a knife as she lay sleeping and "the same thing happened."

In yet another recall, he sees Olivier, who did not immediately die, coughing up blood after the attack.

During a break, Gaston left the courtroom in tears upon hearing the grisly details.

Realizing what he'd done after the stabbings, Turcotte looked to plunge the knife into his own chest. It's something he'd stopped himself from doing earlier.

"I hurt my children and I want to stab myself, but I can't find the knife," Turcotte said.

At some point, Turcotte vomited and fell asleep. He woke up in the morning when police officers began shouting and searching in the rented house.

"The only thing I'm thinking is 'I'm not dead'," Turcotte said. Then he hid under the bed hoping no one would find him.

Turcotte said he can't remember most of the interactions he may have had with most people after that, including police, ambulance technicians and nurses. He remembers waking up at a Montreal hospital.

Turcotte addressed Gaston and her family as well as the children's babysitters on Thursday. He said it all happened under distress and he doesn't understand why the slayings happened.

"I know I could never apologize for what happened," he said. "Just to know the pain and suffering this whole story has caused, I can't accept it."

Turcotte has admitted to causing the deaths of the children, but has denied intent or premeditation.

The defence says the first-degree murder case revolves around Turcotte's state of mind at the time of the killings — and not around whether he performed the act.

The day was marked not only by the gripping testimony, but also by the expulsion of a juror.

The case will continue with 11 jurors because, according to all remaining members, one of their colleagues had exhibited a clear bias in the case. Details of the discussion cannot be reported because they are under a publication ban.

The Crown will begin its cross-examination of Turcotte on Friday.