By Jon Leyne
BBC News, Tehran
Mostafa Naqdi was 15 when he got into a fight which ended in tragedy
Mohammad Mostafaie has a burden probably unique in the world.
He is the defence lawyer for 25 young people, all facing the death penalty.
The files lie thick on his desk. The young clients all stare blankly out in passport photos he spreads out on the table.
This is Iran, the world leader in the execution of juveniles.
It is one of the last remaining countries that still imposes the death penalty on children, for crimes committed under the age of 18.
No-one knows exactly how many juveniles have been executed in Iran in recent years.
International human rights groups say at least six have been killed in 2008.
Mr Mostafaie says 26 juveniles have been executed in the last two years. More than 120 are now under imminent threat.
Take the case of Mostafa Naqdi.
His mother Shahnaz will tell you he is a good Muslim, and an ideal son, who gave up school and worked all hours to help support his family.
One day in 2004, he was riding his motorcycle when he stopped outside a school in an area called Tehran Pars.
As children streamed out of the school, one of them grabbed the bike's ignition key. It should just have been a silly prank. But a fight broke out and then got out of control.
Shahnaz Naqdi has impoverished herself defending her son Mostafa
Mostafa says he grabbed a blunt instrument and lunged out at another boy holding him. Tragically, the blow punctured the lung of the other boy, Masoud, who died later that afternoon.
Mostafa may have been guilty of manslaughter, or possibly it was self-defence. In any case he was only 15-years old at the time. But now he is facing execution.
His mother is distraught, and bewildered.
"This sort of execution is for someone my age not for a 15-year-old boy who can't distinguish between good and bad," she told me.
"How can a teenage boy, who just found himself in the middle of a fight, be expected to understand what is going on?"
It is just the sort of case that Mohammad Mostafaie deals with all the time.
He said that none of his 25 clients had any intention to commit murder.
"They have done the crimes unintentionally," he explained.
"I have talked to all of these people face to face. They talk to me about their childhood and they talk about what happened to them in their childhood.
"When you talk to them, there is no hint of criminality in their face and in their thoughts.
"They can't conceive of the fact that they might be hanged. They are pitiful. Most of the people who are killed by these people were bigger than them, and stronger. They killed them because they were scared."
Mohammad Mostafaie says some children are tricked into confessing
According to Mr Mostafaie, many of the children didn't have lawyers when they were first arrested.
They make damaging statements, he says, and sometimes they are tricked into making confessions. They appear in adult courts where judges are not used to dealing with juveniles.
Listening to his accounts, it appears that much of the treatment of juvenile offenders is as much the result of ignorance and indifference as any actual policy.
Mr Mostafaie described how the parents of one of his other young clients were only told that their son was about to be executed the night before.
No-one even thought to arrange a last meeting between them and their son.
And although there does seem to be strong support in Iran for the death penalty as a whole, the lawyer does not believe most Iranians are in favour of imposing it on juveniles.
"It is interesting when I tell people about these children, or release the information in newspapers," he said.
"People don't want these murderers executed, they are sorry to see them executed. There are lots of people who say they want to stop the executions at any cost."
As for the Iranian government, it recently announced an end to child executions. But a few days later a spokesman made it clear that did not include so called "blood money" or "Qeisas" cases, which make up the vast majority of executions.
"According to the Justice Ministry spokesman, these cases are not technically "execution" but private "retaliation" sanctioned by Islamic law. Something the Islamic Republic is powerless to prevent.
Files of the accused juveniles lie thick on Mohammad Mostafaie's desk
Some human rights campaigners believe the misleading announcement was part of an attempt by Iran to influence events at the UN, where delegates are holding their annual discussion about human rights in the Islamic Republic.
Certainly, Iran is sensitive to any suggestion that its behaviour in any way falls below the most civilised standards.
Iran has signed and ratified the International Convention on the Rights of the Child, which explicitly bans such executions. But it has entered a reservation, the government says exempts it from any provision that goes against Islamic law.
Mrs Naqdi has impoverished herself defending her son Mostafa, though Mr Mostafaie has now taken on the case for free.
In the one-room house she has now moved into, she showed me photos of Mostafa, a proud member of several prison sports teams.
When he was first arrested, he was so under-developed that the authorities did not believe he was 15. Even now, four years later, he is a gangly youth, certainly not grown into a man.
Close to tears
As we looked at the photos together, Mostafa himself came on the phone from prison, his voice firm yet emotional. A tear trickled down his mother's cheek as she spoke to him.
His fate now depends on whether the family of the victim, Masoud, accept blood money, or demand his execution as retaliation.
So, I asked him, did he have a message for the victim's family?
"I know I did something wrong, but I was just a child," he said.
"I did wrong and mankind is like that. But I want to live. I know they are suffering. My family has suffered too. Not as much as them - they have lost their son.
"I just want them to forgive me. I can't do anything else. Their son won't come back by executing me. I can just say that I kiss their hands for forgiveness."