Morteza Abdolali Sarbandi, an Iranian intelligence agent, was killed by Reyhaneh Jabbari after she was lured to flat to undertake interior design work but sexually abused.
Jabbari pleaded self defence but was sentenced to hang for Sarbandi's death. The interior designer's lawyer has warned the sentence could be carried out within weeks.
Iran's Islamic based legal system gives the family of victims the right to grant clemency in capital punishment sentences but Sarbandi's son, Jalal has demanded that Jabbari must change her version of events if she hopes to live.
"Only when her true intentions are exposed and she tells the truth about her accomplice and what really went down will we be prepared to grant mercy," he said.
The son said Jabbari, 26, had conceded a man was present in the apartment where his father was stabbed to death "but she refuses to reveal his identity". His comments come just days after a young Iranian man convicted of murder escaped a hangman's noose in Iran when his victim's mother intervened, slapping him in the face and declaring forgiveness.
The UN says that more than 170 people have been executed in Iran since the beginning of 2014. Jabbari's case has triggered domestic and international condemnation. Iranian actors and other prominent figures have launched an appeal against her execution.
The United Nations and several international rights groups say Jabbari's confession was obtained under intense pressure and threats from Iranian prosecutors. Ahmed Shaheed, the UN's human rights rapporteur on Iran, said that her trial had been deeply flawed and apparently acted in self-defence.
"The Iranian authorities should review her case and refer it back to court for a re-trial, ensuring the defendant's right to due process which is guaranteed under both Iranian law and international law," said Shaheed.
He quoted "reliable sources" as saying that the victim, Sarbandi, had offered to hire Jabbari to redesign his office and took her to an apartment where he sexually abused her. But Jalal Sarbandi insists that his father's murder was premeditated, adding that Jabbari confessed to having bought a knife two days earlier.
"She (also) sent a text message to her boyfriend saying she would kill him," he said. But Shaheed said that Jabbari only stabbed Sarbandi in the shoulder and had called for an ambulance before fleeing the scene..
