According to news reports about the trial, Ms. Jabbari, then 19, met Dr. Sarbandi in 2007 in an ice-cream parlor in Tehran, where he overheard her saying she worked as an interior designer. She made an appointment to visit his practice to assess a possible renovation, though what happened afterward is unclear. Some local websites say they saw each other a couple of other times before Dr. Sarbandi was killed on July 7.

Image Reyhaneh Jabbari, shown in Tehran in 2008, was hanged on Saturday. She had been convicted of murdering a doctor she said had tried to rape her. Credit... Golara Sajjadian/Associated Press

That day, Ms. Jabbari had a knife in her bag, which she testified she had bought two days earlier for her protection. A police interrogator told the semiofficial news agency Mehr in August that the victim had been stabbed in the back while on his prayer rug and had collapsed while running down a staircase shouting, “Thief! Thief!” Ms. Jabbari was convicted of premeditated murder and sentenced to death.

The United Nations office for human rights said there was evidence that Ms. Jabbari’s conviction was based on a confession coerced under the threat of torture. The death sentence against her prompted widespread denunciations, and President Hassan Rouhani’s centrist government tried to get the sentence repealed. The justice minister, Mostafa Pourmohammadi, said in early October that efforts to repeal the sentence were underway and that a “good ending” was in sight, although under the Iranian Constitution, his office has no power over the judiciary.

After the execution on Saturday, the prosecutor’s office in Tehran said in a statement that Ms. Jabbari had been hanged under Iran’s “eye-for-an-eye” law because the victim’s family had refused to forgive her, saying that the local news media had portrayed Dr. Sarbandi as a rapist.

According to the statement, the fact that Ms. Jabbari had brought a knife to the meeting with Dr. Sarbandi, and that he had been stabbed in the back, indicated that she had intended to murder him. The statement also said that Ms. Jabbari had sent one of her friends a text message on the night of the doctor’s death saying, “I will kill tonight.”