A dentist dropped an electrical cable into the water as his wife took a bath at the height of a crisis in their marriage, a court has heard.
Lesley Howell told a friend about the incident at their home in Coleraine, Co Londonderry, before her husband Colin later murdered her along with the policeman husband of his then lover, jurors at Coleraine Crown Court were told.
Margaret Topping revealed how her close friend told her that Howell had dropped the cable into the bath water and she suffered an electrical shock, but she said she was all right.
Mrs Topping said: "She told me almost laughing. She said it was so awful he could not have meant it. But she told me so that I would know."
Police, she said, were later told about what happened in the bathroom, as well as two other issues which Mrs Topping said had raised her suspicions after Mrs Howell was found dead in a car.
She said Mrs Howell told her that her husband had been administering drugs to her, and that she was not planning to give him any of the money that she had inherited in her father's will.
Mrs Howell, 31, a mother of four, and Constable Trevor Buchanan, 32, the husband of Howell's then lover Hazel Stewart were found dead in a car in Castlerock, Co Londonderry, in May 1991 in what was first believed to be a suicide pact.
Howell was jailed for 21 years last December after he admitted murdering the pair by gassing them with carbon monoxide fumes. He later claimed that Stewart, 47, of Ballystrone Road, Coleraine, helped him, but she pleaded not guilty to murder.
On the third day of Stewart's trial on Wednesday, the jury of nine men and three women heard about Mrs Howell's distress over her husband's affair.
Mrs Topping told the court: "She was very sad, embarrassed and very hurt and kept asking, 'Why was I not number one?'. Lesley was distraught for the family and her children, because she still loved Colin."