'I am your judge,' he said as he aimed his weapon at the faces of the prisoners, who were protesting their innocence and loudly complaining about their treatment. 'If you shout again, I can shoot,' he continued. 'If you are brave enough to go out on the streets to protest, you should have the guts to be brave here too.' The book publisher, who had been arrested at his office, said he was speechless. 'What kind of judge,' he recalled wondering to himself, 'wields a gun?' Iran's supreme leader, Ayatollah Ali Khamenei, has called on both sides in the dispute over the June 12 presidential election to cool the tempers of their young supporters. But whereas supporters of defeated candidate Mir-Hossein Mousavi can throw stones or send e-mails, backers of the hard-line incumbent, Mahmoud Ahmadinejad, appear to have the hard instruments of the state at their disposal. The middle-aged book publisher, who was detained in a crackdown against dissidents and alleged rioters, asked that his name not be published for fear of retribution. Although he supported Mousavi, he denies taking part in any unrest. His tale of his week of detention, recounted in an interview Sunday, jibes with accounts of other detainees, many of whom have been released. Some, including political analyst Bijan Khajepour, who was arrested on arrival from a visit to Britain, and reformist Saeed Hajjarian, wheelchair-bound since a 2000 assassination attempt, remain in jail. 'It's never a good time for human rights in Iran, but the scale of what's going on in response to the protests over the results of the elections is beyond anything we've seen in recent times,' said Tom Porteous, a London-based official for Human Rights Watch, which has collected the names of more than 300 people who have been arrested. 'We're very concerned about the potential for the mistreatment of those who've been arrested.' It was 7:30 p.m. on June 20, the day riots engulfed Tehran, when police pounded on the door of the publishing house, located across the street from Tehran University. The publisher, who agreed to be identified only by the initial M, and his colleagues were tabulating accounts and updating their ledger. 'Open up,' the officers demanded. 'Security police!' M opened the door to three security officers, who were wearing helmets and wielding truncheons. The police began swinging the truncheons at the legs and calves of M and his colleagues. 'You were filming the scenes in the streets ... from your balcony,' one officer charged. M offered to let them examine their cell phones. 'Look at them,' he recalled pleading. 'We have not done anything wrong.' Still, they were detained. 'Our commander has video of all who have taken photos and photos of protesters,' one officer told them. 'If your faces aren't there, we will let you go immediately.' Instead, they were locked up in an underground cell near Tehran's Enghelab Square and then taken to another police station in south Tehran. There, the publisher said, he and about 200 other people were crammed into a courtyard and forced to stand beneath the hot sun without food or any place to rest. Nearly 36 hours passed. That's when the gun-waving young man arrived. After threatening the prisoners, he handed out forms that asked a single question: 'Do you accept the charge of being involved in riots against national security and law and order of the country?' Everyone reluctantly acknowledged the charges, M said. After collecting signatures, the man disappeared. Other prisoners said that during these initial hours, they were pummeled by Basiji militiamen who told them they were inspired to crack down by Khamenei's tears at a Friday prayer sermon, which many interpreted as a green light. ' `You have caused my beloved leader to burst into tears,' ' another prisoner said he was told. ' `Now you deserve to be beaten.' ' Hours later, prisoners were packed into two buses. They were headed to the notorious Evin Prison, but M said he was relieved to get there. He knew that's where his family would look for him first. But he was horrified to learn that more than 500 prisoners would be crammed into a cell of about 500 square feet. Older than most of the prisoners, M was designated the cellblock leader, in charge of scheduling four-hour sleeping shifts for the inmates, who had to amble around or stand during the rest of the time, share a single toilet or make quick calls to their family on a single phone. At mealtime, they ate watery bean or noodle soup. To kill time, they debated politics and the nation's future. Prisoners were frequently singled out and pulled away for interrogation. They came back hours later with bruises or with blood in their urine, he said. Some would be pulled out at 8 a.m. and returned 14 hours later, limping and exhausted. Guards told him that about 4,500 people were swept up June 20, with unaccounted numbers jailed in many other places. At one point, he met a family whose members were all jailed. A man, who was with his two sons, said his wife and daughter were in the women's section of the prison. Finally, M was taken for interrogation. He was blindfolded, never getting a chance to see his questioners. But judging from their voices, they were young men. One asked who he was. M replied that he was a mine engineer who for the last 15 years had been accredited to publish books. 'I am sorry that by publishing books, I could not change the destiny of society -- and that I see this bad day,' he said he told them. A second man asked whom he voted for. 'Unfortunately, I could not vote as I was busy and I did not have my birth certificate, but if I had, I would vote for Mousavi,' M replied. 'Do you condone the setting ablaze of banks and breaking windows and the damaging of public property?' the interrogator asked. 'Not at all,' M replied. 'But I understand the frustration of young people and the way they may vent their anger.' The interrogators, seemingly perplexed by M's nuanced answers and calm demeanor, spared him abuse. 'You were mistakenly taken,' an interrogator told him. 'Sorry.' M was allowed to leave Evin on June 27, a week after his arrest. Some prisoners say they were asked to sign statements promising not to take part in any more demonstrations. 'I did not even read it through,' said one Iranian-Canadian dual citizen who was held in Evin for a week. 'I signed it as I was eager to be freed and go back to Canada.' The families of most prisoners had to put up bail. A judge asked for the equivalent of $300,000 to secure the release of a man arrested at a rally near a mosque Sunday who had footage from riots and demonstrations on his cell phone, said a friend. Even though investigators acknowledged a mistake, M's family had to put up the accreditation of his publishing house, his family's economic future. Still, he feels he got off lightly. Many continue to be held in Evin, and more are rounded up daily. The crackdown has made a mockery of Iran's democratic facade, he said. 'Most of the prisoners were shocked that for voting for one of four qualified candidates, they are paying a high price,' M said. 'I think next time in any elections, it will be very difficult to woo people to the polling stations to vote for anyone.' 