Her parents and others told her it would be dangerous to go to Saturday's march, said Golshad.
"I told her, 'Neda, don't go,' " she recalled, heaving with sobs.
But Agha-Soltan was as stubborn as she was honest, Golshad said.
"She said, 'Don't worry. It's just one bullet and its over.' "
Her friends say she, Panahi and two others were stuck in traffic on Karegar Street, east of Tehran's Azadi (Freedom) Square, on their way to the demonstration sometime after 6:30 p.m.
After they stepped out of the car to get some fresh air and crane their necks over the jumble of cars, Panahi heard a crack from the distance. In the blink of an eye, he realized Agha-Soltan had collapsed to the ground.
"We were stuck in traffic and we got out and stood to watch, and without her throwing a rock or anything they shot her," he said. "It was just one bullet."
Blood poured from the right side of her chest and began bubbling out of her mouth and nose as her lungs filled up.
"I'm burning, I'm burning!" Panahi recalled her saying, her final words.
Those nearby gathered around. A doctor tried to help, Panahi said, telling him to put his palm over the wound and apply pressure. A driver coming from the other direction urged the crowd to put her into his car.
A frantic search for a hospital followed. They took a wrong turn down a dead end and switched her limp body to another car.
Along the way, protesters and others screamed at drivers to clear a path in the snarled traffic.
The medical staff of Shariati Hospital made a heroic effort to rush her into surgery, but it was too late. She was dead by the time she arrived at the emergency room, Panahi said.
"This is a crime that's not in support of the government," he said. "This is a crime against humanity."
Iranian authorities have strenuously denied that police were using lethal force to quell the protest.
During tours of the riot scene before, during and after the worst of the melee, there were no signs of security officials using guns.
The prosecutor general's office has launched an investigation into the killing of "several people" Saturday and arrested one "armed terrorist," the website of Iran's Press TV said. At least 13 people were killed in Saturday's rioting.