Bani Yaghoub was due to return to Tehran next year to complete her medical studies and become a specialist in urology. But instead she died in suspicious circumstances in Hamadan prison on October 13.
Eyewitnesses said she was arrested by Iran's morality police while walking with her fiance in a Hamadan city park. Her fiance was released an hour later, but she was kept in prison overnight.
The next day, her lifeless body was handed over to her parents with the police claiming she committed suicide by hanging herself.
"Now people see that even an ordinary person does not have basic security; and a person simply can get arrested on a street and, instead of returning home, their bodies are buried in a cemetery." -- journalist Isa Saharkhiz
Bani Yagoub's family, however, say they have no reason to believe that their daughter would take her own life.
Her father, who reportedly works at an Islamic Revolution Guards Corps facility, accuses the police of assaulting and murdering his daughter.
The family also says her brother had spoken with her over the phone 15 minutes before the time the police claim she killed herself. Bani Yaghoub's brother said there was no indication she was minutes away from taking her life.
The family says Bani Yaghoub's body was bruised and that there was blood in her nose and in her ears.
Bani Yaghoub's death has caused worries in Iranian society about basic civil liberties and personal safety.
Iran's state media has briefly reported the official version of the event. The independent media, however, have been covering all sides of the story and public reaction to her death.
Isa Saharkhiz, an independent journalist and a member of the Association of Press Freedom in Iran, says the details of this woman's tragic death in prison have reached the Iranian people through the country's independent media and foreign news agencies.
Saharkhiz says that under the Islamic regime, Iranians have somehow become accustomed to political activists or independent journalists being arrested and even killed in suspicious circumstances, but this ordinary woman's death while in custody has shocked society.
"Now people see that even an ordinary person does not have basic security; and a person simply can get arrested on a street and, instead of returning home, their bodies are buried in a cemetery," he tells RFE/RL. "It has become a very sensitive issue in our society and created many questions."
Call For Full Investigation
In an open letter to the head of the Iranian judiciary this week, a group of former Iranian parliamentarians called for a thorough investigation into the circumstances around Bani Yaghoub's death.
The Iranian Alumni Association of Majlis Representatives, which brings together more than 400 former Iranian parliamentarians, urged Ayatollah Hashemi Shahrudi to fully investigate the case in order to answer all outstanding questions.
Bani Yaghoub's death attracted more attention this week with high-profile lawyer and Nobel Peace Prize laureate Shirin Ebadi discussing the possibility of an autopsy being done.
Ayatollah Hashemi Shahroudi (Fars)
Mehrangiz Kar, an Iranian-born, human-rights lawyer and author based in the United States, says whether the cause of death was a murder or a suicide, the police and judiciary are responsible for this tragic event.
"Who, how, and why could push such a young girl -- one who had a bright future ahead of her -- to the point of anxiety and despair?" she tells Radio Farda. "No matter what has happened, the authorities are responsible for this death."
Both Kar and Saharkhiz say the chances are slim that the authorities would hold any police officer or a prison worker responsible for Bani Yaghoub's death.
They say the authorities cannot ignore the case, which has taken on a high profile with all of the media coverage. But they believe officials will probably drag on the investigation for months and even years until publicity around it eventually fades.
Bani Yagoub's death in prison was similar to that of Zahra Kazemi, an Iranian-Canadian photographer who was arrested while taking pictures outside Iran's notorious Evin prison in 2003. Kazemi later died amid allegations that she was severely beaten, tortured, and possibly raped in prison. Prison officials, however, said Kazemi had a stroke.
Earlier this year, Iran launched a "public security and moralization campaign" during which many citizens, including many women, were arrested and questioned for their alleged un-Islamic attitude, such as Western-style hairdos or outfits.
Unmarried men and women cannot walk together in public holding hands.
There are many cases in Iran when young men and women have been arrested for walking together. However, most of them were later released after paying a fine or receiving other punishments such as flogging.
(RFE/RL's Radio Farda contributed to this report.)