The prison authorities hanged Miss Darabi, 23, even though the head of Iran's judiciary granted her a two-month stay of execution on April 19 amid international outrage over her case. They also did not give her lawyer the required 48 hours notice.
Horrific new details have emerged of her last desperate plea for help from Rasht prison as jail guards came to lead her away.
Miss Darabi made a tearful call early on Friday to her parents to say she could see the gallows and noose, according to media reports from Tehran.
"Mother they are going to execute me, please save me," she pleaded. But a prison official then grabbed the phone and told her distraught mother: "We are going to execute your daughter and there's nothing you can do about it."
Apart from the rank cruelty of taunting her parents by telephone as they dragged her to the gallows, the regime's treatment of Ms. Darabi has other dark implications.
The execution of a young woman whose case has become an international cause célèbre is a further damaging blow to President Barack Obama's attempts to thaw US relations with the Islamic regime. Roxana Saberi, an American-Iranian journalist, is on hunger strike in a Tehran prison after being convicted of espionage in a show trial last month.
Miss Darabi's case gained widespread attention after moving paintings and drawings that she made in her prison cell were shown around the world. She developed her talent as a painter behind bars.
Iran, Saudi Arabia and Yemen are the only countries to execute people for crimes committed when they are under 18. Miss Darabi was 17 when she admitted killing her 58-year-old uncle in a burglary in 2003 but she quickly retracted the confession, saying she had taken the blame to save her boyfriend.
I am a firm believer in capital punishment in the USA, and even disagree with the ban here on executing minors -- I think a 16-year-old has the capacity to act as an adult and should be punished as one if he or she is guilty of capital murder.
But I don't support executing a person whose guilt is not conclusively proven, whose due process in the judicial system has not been taken to its conclusion and whose execution violates all of the standards and safeguards that a society places on its own criminal justice system. It's plain that the execution of Ms. Darabi was a political demonstration that the Iranians will do with their citizens and their policies whatever they wish, without regard to outside influence... other than the military kind, that is.
As the article notes, that bodes ill for the American journalist Roxana Saberi. It also bodes ill for the prospect of a peaceful negotiated resolution to the dispute over Iran's nuclear programs. (But I hear tell the Israeli Air Force is practicing long-range air-to-air refueling.)