The man in Surrey, UK, was acquitted of the murder in 2017, after convincing the court that he acted in self-defense.
His story was corroborated by the couple's children, who were under 10 at the time. Both the father and the child had knife wounds when police arrived at the scene, Sky News reports .
Four years later, the child told a therapist that he had been manipulated into lying. According to the child's new testimony, the father killed the mother - and also involved the child in his murder plan.
"The child's part of the plan was to distract the mother by saying 'hold out your hands, I have a surprise for you'. The child would then place a drawing in the mother's hands," the prosecution said.
The man then stabbed his wife in the throat, then turned the knife on himself and also cut his child in the arm. He then instructed the child to lie about the incident.
On Friday, the man was convicted of murder and child abuse. The sentence will be announced in January.
