Iranian security forces killed a teenage boy by firing a shotgun at him at point-blank range in the city of Mashhad, sources have told BBC Persian.
Abolfazl Adinezadeh, 17, skipped school to join anti-government protests on 8 October, but he never returned home.
The sources cited a doctor as saying it was fired less than 1m (3ft) away.
"What crime had he committed, that you sprayed his stomach with 24 birdshot?" Abolfazl's father pleaded at his funeral, a video showed.
Abolfazl's parents initially had no idea what had happened to him after he took part in the protests, according to the sources.
It was not until the next day that the education ministry telephoned and told them to pick him up from the local police station.
But when they got there, they were told that he was dead.
"You zip your mouth and do not talk to media," Abolfazl's father was warned at the police station, the sources told the BBC.
Authorities have accused "rioters" backed by Iran's foreign enemies of killing Basij members and other security forces during the current unrest.
Plainclothes security personnel were also present during Abolfazl's funeral, shushing mourners who wanted to express their anger, according to the sources.
Abolfazl's aunt held up a picture of him over his grave, but a female agent snatched the frame and put it under her veil, they said.
Some mourners were also stopped after the funeral and asked to delete the videos from their mobile phones.
Abolfazl's mobile has not been returned to the family yet, the sources said.
Footage of Abolfazl Adinezadeh shows a happy teenager dancing and laughing all the time. According to the sources, he was known for making everybody smile.
After school, he worked until 22:00 at a shop fixing mobile phones.
Recently, he had become increasingly angry about corruption, the death last month of Mahsa Amini - the 22-year-old woman who fell into a coma after being detained by morality police - as well as the footage of other women being beaten and killed in the streets, the sources said.
Iran's Human Rights Activists News Agency (HRANA) estimates that 244 protesters, including 32 children, have been killed by security forces in the crackdown. It says more than 12,500 others have been detained, many of them young people and children.