Robert Penny's second wife denies they were having an affair while he was still married to his first wife, whom he is now suspected of murdering.
Margaret Penny and her hairdresser Claire Acocks, 49, were found beaten and stabbed to death at the Old London Coiffure hairdressers in the western Victorian town of Portland in May 1991.
Years on, detectives suspect Mr Penny might have been motivated to kill his 58-year-old spouse because he was having an affair with a younger woman who became his second wife.
However, that woman, Kim Penny, on Tuesday denied an affair with Mr Penny while he was still married to Margaret.
"No, I respected them too much for that, I wouldn't do it," she told a second inquest into the deaths.
She said she never suspected her husband was involved in the murders.
"They both had been a loving couple," she said.
"I've never suspected at all that Robert was involved in what happened."
Bob Lowther, the detective in charge of the Portland criminal investigation unit at the time, said to this day he is uncertain what weapon was used.
The first time he heard about the possibility of a tail comb being used in the murders was in 2015.
Mrs Penny's daughter Alexis Rizio told the inquest Mr Penny mentioned to her a comb was possibly used as a weapon.
"I believed he had formed the understanding the weapon used in the murders was a hairdresser's comb. I don't know how he came to believe this," she said.
Mrs Penny said she didn't have any contact with Mr Penny until August, 1991, three months after the murders.
She invited him to stay with her at her Malvern East unit in Melbourne, which he did.
She said their relationship didn't become intimate until about October that year.
However, her neighbour Elena Irma Jomantas recalled Mr Penny visiting the Malvern East unit complex a month before the murders.
The inquest also heard Mr Penny's son Tony witnessed his father and Mrs Penny being affectionate during a trip to Portland in June, a month after the killings, and was distressed by it.
But Mrs Penny repeatedly rejected the relationship with Mr Penny began sooner than August 1991.
Mr Penny was initially ruled out as a suspect in the double murders because the crime seemed too violent for the retiree to have committed.
He was charged over the murders in 2015 after new evidence came to light, but died before facing a committal hearing.
The inquest continues.