An Iranian teenage girl was sexually assaulted and killed by three men working for Iran's security forces, according to a leaked document believed to have been written by those forces.
It enabled us to map what happened to 16-year-old Niki Šakarama, who disappeared during anti-government protests in 2022.
Her body was found nine days later.
Authorities claimed she killed herself.
We have submitted questions regarding the allegations in the report to the Iranian government and the Revolutionary Guard.
They didn't answer.
The report, labeled "top secret," summarizes statements made during a hearing on Nika's case by the Islamic Revolutionary Guard Corps, also known as the Revolutionary Guards or Iran's Revolutionary Guards - the security force that maintains the country's Islamic order.
It lists, as he writes, the names of her killers and high-ranking commanders who tried to hide the truth.
The document contains disturbing details about the events in the back of the van where Nika was being held by security forces.
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Some of the details listed are:
- One of the men molested her while sitting on top of her
- Although her hands were handcuffed, she resisted, kicking her feet and cursing
- Admitting that her behavior provoked the men present to beat her with clubs
As there are many fake Iranian official documents in circulation, the BBC spent months checking every detail with multiple sources.
Our extensive investigation shows that the papers we obtained provide a chronological account of the teenage girl's movements immediately before her death.
There have been many reports of the disappearance and death of Nika Shakarama, and her image has become synonymous with women's struggle for greater freedoms in Iran.
During the street protests that took place across Iran in the fall of 2022, her name was chanted by many who oppose the country's strict headscarf [hijab] rules.
A few days before her disappearance, a movement was founded in Iran called Women, life, freedom (The Women, Life, Freedom), in response to the death of 22-year-old Mahsa Amini.
She died of injuries sustained in police custody where she was detained on charges of not wearing the hijab properly, according to the findings of a United Nations (UN) fact-finding mission.
In the case of Nike, her family found her body in a morgue more than a week after she disappeared during the protests.
However, Iranian authorities have denied that Nika's death was linked to the demonstrations and, after conducting their own investigation, said she committed suicide.
Just before she disappeared, Nika did taken in the evening of September 20 near Laleha Park in the center of Tehran, standing on a container and lighting hijabs.
People around her chanted "death to the dictator," referring to Iran's supreme leader, Ayatollah Ali Khamenei.
What she could not have known at the time was that she was under surveillance, which was clearly stated in the classified document.
In the document addressed to the Commander-in-Chief of the Revolutionary Guard, it is stated that the report is based on extensive conversations with the Guard teams that secured the protest.
The report begins with the sentence that the demonstrations were secretly monitored by several security units.
It is said that one of them, Team 12, suspected that the teenager was "the leader of the demonstration, because of her unconventional behavior and because she often used a mobile phone".
The team sent one of its operatives into the crowd, posing as a protester, to verify that Nika was indeed one of the leaders of the demonstration.
Then, according to the report, he called his team to come and arrest her.
But she escaped.
Her aunt previously told the BBC Persian service that Nika called a friend that night and said that the security forces were looking for her.
It was nearly an hour before she was spotted again, the report said, when she was taken into custody and put into the squad's vehicle - an unmarked van with a freezer in the back.
Nika was in the back of the van with three members of Team 12 - Arash Kalhor, Sadeg Monjazi and Behruz Sadegi.
Team leader Morteza Jalil was in front with the driver.
The group tried to find a place to take her, the report said.
They tried to leave her in a nearby temporary police camp, but they couldn't because it was overcrowded.
They then headed to the detention center, about a 35-minute drive away, whose commander had initially agreed to take Nika, but changed his mind.
"The defendant [Nika] kept cursing and chanting," he told investigators.
"At that time, there were 14 other detainees in the station and I thought that she could disturb the others.
"I was afraid it would cause a riot."
Morteza Jalil again called the Revolutionary Guard headquarters for further instructions, the report said, and was told to go to the notorious Evin prison in Tehran.
On the way, he said, he heard the sounds of blows coming from the dark back of the van.
From the statements of the men who guarded Nika in the back mentioned in the report, we know what he heard.
One of them, Behruz Sadeghi, said that from the moment Nika was put back in the van after she was not admitted to the detention center, she was cursing and shouting.
“Arash Kalhor gagged her with his socks, but she began to struggle.
"Then Sadeg [Mondzazi] laid her on the freezer and sat on her.
"The situation has calmed down," he told investigators.
"I don't know what happened, but after a few minutes she started swearing.
"I couldn't see anything, I just heard fighting and hitting".
But Arash Kalhor provided more gruesome details.
He says that he briefly turned on the light on his mobile phone and saw that Sadeg Monjazi had "his hand in her pants".
Arash Kalhor said they lost control after that.
"He doesn't know... who [did it], but he could hear... the baton hitting the defendant [Nika]...
"'I started kicking and punching, but I really didn't know if I was hitting our guys or the accused.'"
But Sadeg Monjazi's statement is completely different from Arash Kalhor's statement, which he said was motivated by professional jealousy.
He denied putting his hand in her pants, but said he could not deny he got "turned on" while sitting on top of Nikki and that he touched her bottom.
He said this provoked Nika, who, although her hands were tied behind her back, managed to scratch and kick him, causing him to fall over.
"She kicked me in the face, so I had to defend myself."
Mortez Jalil, who was sitting in front, ordered the driver to stop the vehicle.
He opened the back door and saw Nika's lifeless body.
He stated that he cleaned the blood from her face and head "which were not in good condition".
This statement corroborates Nika's mother's account of what she looked like when she was found at the morgue, as well as Nika's death certificate obtained by the BBC Persian service in October 2022, which stated that the death was due to "multiple blunt force injuries with a hard object".
Team leader Morteza Jalil admitted that he did not try to find out what happened.
"I was only thinking about how to transfer her somewhere and I didn't ask anyone questions.
"I just asked, 'Is he breathing?' I think Behruz Sadeghi replied: 'No, she's dead'".
Jalil called the headquarters of the Revolutionary Guard for the third time, this time with "bloody hands".
On that occasion, he spoke with a senior officer, codenamed "Naim 16".
"We already had deaths in our stations and I didn't want the number to increase to 20," Naim told 16 during the investigation.
"Bringing her body to the base wouldn't solve anything."
Jalil told him to simply "throw her out on the street".
Jalil said they left Nika's body in a quiet street under Jadegar-e-Emam highway in Tehran.
The report concludes that the sexual harassment caused a fight in the back of the van, and that Niki's death was the result of the blows inflicted on her by the 12th team.
"Three batons and three electric shockers were used.
"It is not clear which of the blows was fatal," the document states.
The report contradicts the authorities' accounts of what happened to Niki.
Almost a month after her funeral, state television announced the findings of the official investigation, according to which Nika jumped from the building.
Surveillance camera footage was shown showing a person, claimed to be Nika, entering the apartment block.
However, Nika's mother told the BBC Persian service by phone that she could not "under any circumstances confirm that this person is Nika".
"We all know they are lying," Nasrin Shakarami told the BBC about the authorities' claims of the protesters' deaths.
The BBC investigation was not only concerned with the content of the report, but also whether it can be trusted as an authentic document of the investigative process that was actually carried out.
Sometimes documents that appear to be official and other materials circulating on the Internet are found to be fake.
However, most of these forged documents are easy to recognize because they are clearly different from the official format - they contain irregularities in spacing and headings, or significant grammatical or spelling errors.
Also, they may contain the wrong official slogan or designation for the year of manufacture, or for example, an anachronistic name of a government agency or department.
Another indicator is the language that does not conform to the very specific style mostly used by Iranian official institutions.
The document that was the focus of our investigation contains several such inconsistencies.
For example, the abbreviation for the police "Naja" mentioned in the report was known at the time as "Faraja".
To further verify the credibility of the report, we gave it to a former Iranian intelligence officer who has seen hundreds of original documents.
He called the archives of the Revolutionary Guards, using the official password that is assigned every day to high-ranking intelligence officers in Iran, to check whether this report really exists in the case file and what it is about.
It has been confirmed to him that it exists, and that the report number shows that it is part of a 322-page dossier on anti-government protesters from 2022.
Although we can never be 100 percent sure, this has convinced us that the document is genuine.
Thanks to his access to the Revolutionary Guard, we were able to uncover another secret - the identity of "Naim 16", the man who told the team to dispose of Nika's body.
To find out, the former intelligence officer made another call - this time to someone from the Iranian military structure.
He was told that Naim 16 was the call sign of Captain Mohamed Zamani, who serves in the Revolutionary Guard.
That's one of the names of people who attended the five-hour hearing into Nika's death, which was summarized in the report.
We have submitted questions about these allegations to the Revolutionary Guards and the Iranian government.
They didn't answer.
The men responsible for Nika's death, as far as we know, have not been punished.
The answer to the question why they did not can be found in the document itself.
All members of Team 12 who were at the hearing are listed in the report, and to the right of their names is the group they belong to: "Hezbollah".
That name refers to the Iranian paramilitary group Hezbollah, which is not affiliated with the Lebanese group of the same name.
Its members are used by the Revolutionary Guard, but they sometimes operate without its authority, as the report appears to confirm:
"Since the above-mentioned persons belonged to Hezbollah forces, it was not possible to pursue this case without obtaining the necessary promises and security guarantees," it said.
However, the Revolutionary Guard officer Naim 16 received a written warning, the document added.
Security forces killed as many as 551 demonstrators during the protests of the Iranian movement Women, life, freedom, most with firearms, according to data from the UN fact-finding mission.
The protests were suspended after several months due to a bloody confrontation between the security forces and the demonstrators.
Then the Iranian morality police made peace, but earlier this month a new crackdown on those who violate Islamic rules began.
Among those arrested is Nika's older sister Aida.
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