But, speaking in conciliatory tones for the first time, Frank Gilford said he had not ruled out a plea for clemency on the women's behalf.
"There is no foregone conclusion that we are going to say 'right, we want their heads chopped off'," Mr Gilford told Reuters news agency in a reference to the public beheading that could await Deborah Parry, 38, and Lucille McLauchlan, 31, if they are convicted of killing Yvonne Gilford last year.
Mr Gilford and his mother, Muriel, 84, have the right to demand the death penalty under Saudi law. Until now, his stance has appeared to be firmly in favour of beheading, but yesterday his tone sounded softer.
"We have not ruled out the death penalty, but then again we have not ruled it in," he said from his home in Jamestown, north of Adelaide. "We have never demanded it definitely had to be the death penalty. We have not knocked back our option of exercising our rights [to grant] clemency.
"What we are looking at, is for the court to make a decision and then we can say right, we can look at it." Asked how he felt with the Saudi court's verdict expected soon, Mr Gilford said: "Not very comfortable. It is not a situation I would wish on my worst enemy, it is a position I do not feel any person should be put in."
His sister's body was discovered in her room at the King Fahd medical complex in Dhahran last December. She had been stabbed, beaten and suffocated.
Yesterday, Mr Gilford launched what appeared to be a legal move to outflank the British nurses' lawyers in an Australian court. The women's representatives had argued that his mother was not competent to demand the death penalty - which must be called for by the victim's family unanimously - because she was suffering from Alzheimer's disease.
Mr Gilford applied to be made her guardian so that he could make her demand for her.
However, he said his motives were not designed to guarantee a death penalty. "My motivation is to look after my family unit. All this is doing is to pick on a poor old lady who is 84 and whose only crime is to be old and feeble and to have a daughter who was cruelly murdered."Reuse content