Allan Schoenborn has pleaded not guilty to three counts of first-degree murder in the deaths of his children in Merritt, B.C., in 2008. (CBC)

A father charged with the first-degree murder of his three children in Merritt, B.C., said he killed them because he "thought they were being molested," according to an audiotaped conversation played during his trial Wednesday.

The statement was heard in a secretly recorded conversation between the children's mother, Darcie Clarke, and the father, Allan Schoenborn. The taping, arranged by police without Schoenborn's knowledge, took place at a jailhouse meeting.

The case drew national attention when the children were found dead in Clarke's trailer home in April 2008 — in part because Schoenborn led police on a nine-day search before he was captured by a hunter in the hills near the southwestern Interior community.

Schoenborn is on trial on allegations he smothered his sons, aged eight and five, and fatally stabbed his 10-year-old daughter.

Schoenborn gave Clarke the explanation after she repeatedly asked him why he killed the children.

"I thought they were being molested," Schoenborn is heard saying on the tape.

He promised Clarke he didn't torture the children, but said the killings weren't quick because he didn't know what he was doing.

"It came in one big flood. There was nothing I could do about it if I tried," he said.

The court did not hear why Schoenborn believed his children were being molested, or whom he thought was responsible.

Clarke sobbed as she spoke of returning to her home to find the cold bodies of Max, aged eight, and Cordon, five, curled up on a couch, and then Kaitlynn, 10, in her bedroom wrapped in her favourite blanket, dead from stab wounds.

She said she recalled screaming, "No, no, no, it's not happening. It's not real," as she went from one dead child to another.

Crown says motive was revenge

Clarke testified the murders happened the day after she told Schoenborn their marriage was over.

Clarke also said that she and Schoenborn saw each other several times on the day before the killings and he appeared depressed and sad about their not being together — but nothing he said or did that weekend made her fear for the safety of her kids.

Darcie Clarke's three children, 10-year-old Kaitlynne, eight-year-old Max and five-year-old Cordon, were found slain in their trailer home. (CBC)

Schoenborn was staying with their children in Clarke's trailer while Clarke stayed at her mother's place, much as they had done on other occasions when he came up from Vancouver to visit, she testified.

The Crown alleges the murders were an act of revenge against Clarke.

Testimony at the trial last week also suggested Schoenborn may have tried to commit suicide in the trailer, but decided to flee — leading police on the long chase.

With files from The Canadian Press