Omar Mohammed is an historian and a “citizen journalist,” as some people say. He is an Iraqi from Mosul, a city that was occupied by the Islamic State from June 2014 to July 2017. Mohammed chronicled this occupation, at great risk to himself. He wrote an anonymous or pseudonymous blog, known as “Mosul Eye.”

Why did he do it? Why did he take the risk? He tells me when we sit down at the Oslo Freedom Forum, the annual human-rights gathering in Norway’s capital. Omar Mohammed is one of the most extraordinary people you will ever encounter.

He was born in 1986, during the Iran–Iraq War. His father was among the conscripts in the Iraqi army. The war finally ended in 1988, having begun in 1980. Saddam Hussein and the Ayatollah Khomeini decided they had killed enough people for no real reason.

That’s how Mohammed puts it to me, with perfect sardonicism.

Mohammed grew up under Saddam Hussein — in that “republic of fear,” to quote the title of Kanan Makiya’s memorable book. Mohammed’s grandmother told him, “Be careful what you say, because even the walls have ears.”

That was precious advice, but Omar Mohammed was a spunky kid. One day in school, when he was about 14, he was arrested by the director of the Baath office in the school. (The Baath was Saddam Hussein’s ruling party.) The party director was also the principal of the school. Every kid was supposed to pay dues to the party, but Omar balked. “Why should I pay?” he told them. “I get money from my father to buy things for me, not to give to you! I have been studying, and now I want to go buy something from a shop. I will not pay! Stop taking money from me!”

After a couple of hours, Omar’s brother arrived at the school and artfully bailed him out. “Just a silly kid,” said his brother, essentially. “He means no harm, pay him no mind.” Omar’s defiance could have been very bad for the family.

As he explains to me, state agents were always spying on people, using their children to gather information on them. They might see a child on the street and say, “Oh, hi, how are you? How’s your father? Has he said anything about Saddam lately?” All very innocent, you see.

Omar Mohammed wanted to study chemistry in college, for he loved that science. He decided on history, however, because he had questions — questions not answerable by chemistry but perhaps by history. These had to do with Mosul and beyond. “How did we get to this point? What is the truth?”

Mohammed also loved the English language, by the way. He saw a movie in English when he was 16 and was frustrated that he couldn’t understand it. So he set about learning English, painstakingly. He even created his own dictionary. He has a particular love of Milton, awed by that poet’s genius. In the past, Mohammed used several pseudonyms, including “Maurice Milton.”

“Maurice”? The name of a character in Madagascar, the animated movie from 2005.

In 2012, Mohammed defended his dissertation at the University of Mosul. It was on the French occupation of Egypt, and a professor of his told him something jarring: “You are a dangerous man in our community. You are a threat to our community.” How was that? Mohammed followed the facts wherever they led him, refusing to tailor a line to politics.

Incidentally, he is an admirer of Bernard Lewis, the late Middle East scholar, despised by many precisely for his pursuit of the historical truth, however inconvenient it may be, politically or socially.

In 2013, Mohammed began teaching at that same University of Mosul. When the Islamic State occupied the city, a year later, he lost his job. The occupiers declared history an “unuseful science.” They destroyed Assyrian, Christian, and Islamic monuments. They foisted their own version of history on the city.

Mohammed was absolutely determined to counter this. He was also determined to chronicle everything the Islamic State was doing.

By the way, Mohammed prefers this term, “Islamic State.” He prefers it to “ISIS,” “ISIL,” “Daesh,” etc. For one thing, the world should know that these terrorists took advantage of Islam. But, more specifically, Muslims should know it — and they should feel a duty to reform, in order to prevent another group from taking similar advantage.

In Mosul, Mohammed pretended to be a sympathizer with the Islamic State. He grew his hair and beard out; he dressed in the prescribed way. And he saw everything. What, exactly? Oh, the usual: floggings, beheadings, stonings — the cruelest behavior imaginable by man. Mohammed says that the treatment of the Yazidi people was especially unspeakable.

I will relate just one story — about Islamic State behavior in general — if you can bear it. Two women were accused of adultery. The terrorists stoned the women, according to what they regarded as the law. One woman died after a few minutes. The other did not. She was bleeding badly and almost dead, but she was hanging on to life, somehow. According to the terrorists’ own view of the law, the woman should have been let go, for she did not die in the initial stoning.

But one man said to another, “Shoot her.” The other man said no — instead, “Let’s play.” They told the woman to run away, and if she managed to do so, she would be free. The woman, crazed, ran in circles. She probably thought she had made it to safety. Then the men shot her.

As Omar Mohammed relates such stories to me, he says, “Bear in mind, I’m telling you this, the best I can, but there is really no language that can describe it.”

He recorded the names of the dead — as many of the dead as he could find out about — and he did it for a simple reason: He did not want them forgotten.

He also paid attention to the killers, the men of the Islamic State. What were they like? They were from many different countries. Some of them spoke no Arabic at all. Some of them were utterly hardened — zealous monsters. Some of them were simply deranged. Others were confused, or misled. Mohammed could see clearly that some were afraid. He could see the fear in their eyes. These men seemed to be saying, “What have I gotten myself into?”

Mohammed did his writing at night. He had a three-step process. First, he wrote on paper. Then he took a scanner and copied the paper that way. Then he typed the words into a laptop. When it came to communicating with the world, he used Facebook, Twitter, and other platforms. He also jotted down copious notes for later use. And he did all this in stark terror. When the wind ruffled the curtains, he jumped. They are here to get me, he thought.

Of supreme importance to him was that his writings survive. “If they killed me, I wanted it to be worth it,” he tells me. “I wanted proof for the future that this is what happened in Mosul under the so-called Islamic State.” He knew how history can be falsified, bent, airbrushed, or outright obliterated.

He took elaborate measures not to be traced online. And he kept two laptops: one to work on and one that was “clean.” “When they come to your house, the first thing they say is, ‘Your phone, your laptop.’” Mohammed wanted something to present to them, if they came. He would give them the “clean” one, which had never been connected to the Internet and which had nothing but religious texts and nice pictures on it.

He had a motto, which he dubbed his “golden rule.” It is a two-part rule: “Trust no one, document everything.” The first part relates to what his grandmother told him, back in Saddam days. And the second? “They fear this,” says Mohammed (“they” being the Islamic State and other persecutors, and “this” being documentation). “They fear history, and they fear those who write history from authority.”

I interject, “Then they must sense that what they’re doing is wrong.” “Of course they sense it!” Mohammed exclaims. “They know.” I mention the “White Helmets” in Syria, who try to rescue the bombed and who are witnesses to war crimes. The Assad regime and its allies hate them intensely, and try to wipe them out. Mohammed mentions Erdogan, the Turkish strongman, who locks up journalists, academics, and others by the thousands.

Mohammed told no one about his work, not even his family — especially not his family. He did not want to put them in danger. He did not want to impose on them the burden of his secret. Mohammed worked under a tension that was almost unbearable. “It’s only because of music that I survived,” he says.

Yes. He listened to music — especially as played by Itzhak Perlman, the Israeli-American violinist. “He’s my man,” says Mohammed. One night, Mohammed was engulfed in darkness, on the verge of giving up. He put on music from Schindler’s List, the Holocaust movie from 1993, with a score by John Williams. Perlman was the featured soloist. Mohammed listened to “Jewish Town,” among other tracks. “When I listened to this music,” he says, “I felt like someone was injecting life into my heart.”

Perlman read about Mohammed’s admiration of him and expressed the wish to meet him. Mohammed then wrote Perlman a five-page letter. They have not met yet, but almost surely will. “When I wrote him the letter, I thought, ‘Now I have to make sure I stay alive until I meet him,’” says Mohammed.

At the end of 2015, he decided he had to flee Mosul. “They were getting closer to me,” he says about the Islamic State, and he was fearful for his family. “I accepted the price of what I was doing: death. But I could not accept this for my family.” Eventually, he received asylum in Europe. He continued to report on Mosul, using information gleaned from those living there.

It was only at the end of 2017, months after the downfall of the Islamic State in Mosul, that he revealed his identity to the world. He was extremely nervous about it. He couldn’t sleep the night before. He was especially nervous about what his mother would say. When he got her on the phone, she said, “Boy, I always suspected you.” She understood that, in not telling her, her boy had only been trying to protect her.

And how did Mohammed feel once his identity was out? “I felt free for the first time. Like a bird set free. I was flying.” Online, his readers over the years hailed him with such words as “hero.”

People at war see terrible, terrible things. In Mosul, Omar Mohammed saw more than his fair share. How does he cope with it, mentally? “To be honest, after I left Mosul, it took me almost six months to realize I was alive.” He felt as though he were dead. What he saw should exist only in horror movies, he says — but he saw it in real life, with his own eyes. Today, “I am trying to keep my strength, because I still have lots to do. You have to keep yourself strong to keep going — but I know that I am tired.”

Very recently, he visited the Jewish Museum in Berlin, which has a section called “Memory Void.” On the floor are 10,000 faces, punched out of steel, meant to represent the dead. The murdered. Mohammed could not help thinking of a deep, deep hole in Mosul, where the Islamic State shoved in the people they had just executed — “hundreds of people,” says Mohammed.

Of course, this is the way it was at Babi Yar in Kiev, and in countless other places.

Mohammed is writing a book, telling the full story of the Islamic State in Mosul. This coming semester, he will be a “world fellow” at Yale University. He is an academic, and that will be his career.

Not long ago, he spoke with an elderly member of the European Parliament, who said that Mohammed reminded him of himself. The man had come through World War II, and he cited the imperative of post-war Europe: never again Auschwitz. Omar Mohammed has much the same feeling. “I want to use my knowledge of history to prevent the Islamic State from ever happening again. That’s my main goal now.”