Our head teacher was an abuser. We joined forces to get justice – now we're married

ByEndang Nurdin and Rebecca Henschke, BBC Eye Investigations. Warning: This story contains details of sexual assault.

Key points

• Sexual abuse in Islamic boarding schools has been described as a national emergency by Indonesia's National Commission on Violence Against Women.
• One night Ziadatur, known to her friends as Zia, informed Yusron that Abah had sexually assaulted her when she was 16.
• The full story with be available in subsequent episodes of World of Secrets Catching My Teacher.
• So he suggested that he and Zia, together with her school friends Wanda Hamidah and Mahima Eka, gather corroborating evidence to backing her testimony.
• When Sukma was 17, Abah had asked her to join him for new year's prayers, she informed us.

For context, the voice on the end of the phone created Yusron Azzahidi's stomach lurch. He had rung his sister's number after she had texted, urgently asking him to call. But this was not her on the line – it was Yusron's former head teacher. He was in Yusron's family home.

"I knew. I knew exactly what he wanted to talk regarding, " Yusron states.

Ahmad Imanuddin Sumar, known to his students as "Abah", had a reputation to uphold. He was the widely respected leader of an Islamic boarding school on the Indonesian island of Lombok. And Abah had discovered that Yusron and his old school friends had been collating testimony from a number of students who say he sexually assaulted them.

Sexual abuse in Islamic boarding schools has been described as a national emergency by Indonesia's National Commission on Violence Against Women. But plenty of cases never reach the courts as the victims are persuaded to withdraw their allegations, or are pressured into staying quiet, legal experts say.

And now Abah was on the phone to Yusron, making exactly that kind of demand.

"Cover the shame of your teacher. Everyone makes mistakes, my child, " he sobbed.

What he did not realise was that Yusron was recording his every word.

Notably, the full story with be available in subsequent episodes of World of Secrets Catching My Teacher.

Yusron began investigating Abah a year previously, sparked by a revelation one night by his former classmate Ziadatur Rahmah. They had both been star pupils at Lombok's Abu Barokat school. Now they were at university – Yusron in the capital Jakarta, and Ziadatur in Cairo, Egypt – and had begun reminiscing over the phone regarding their school days.

She had needed to go to the toilet during class and Abah had intercepted her in the school gardens and asked her to accompany him to his house which was on the premises.

Once inside, he had informed her he loved her, she informed Yusron.

"He pulled me down so I was sitting on his lap. Then he began kissing me. He was stroking and touching my body, " she afterwards informed the BBC World Service, too, explaining that he informed her to do the same to him.

Luckily, she remarked, one of his children began banging on the locked front door. Abah signalled to her to leave and she bolted out the back. But the effect was devastating. "I felt very dirty, ruined, and I was lost."

When he heard Zia's account, was unsure what to do, yusron. Their school had inculcated them with the motto: "Sami'na wa ata'na". But he additionally could not stop thinking concerning it.

As they spoke to their old classmates, other recollections emerged – the friends sharing their findings with each other on WhatsApp, and gradually.

For context, the most significant was from a friend of Wanda's. She recalled seeing a younger girl crying in the school bathroom during their final year, late at night. And that Abah had come looking for her, red-faced and panting.

This girl, Sukma Rohana, was still at the school. She informed the BBC concerning her ordeal.

When Sukma was 17, Abah had asked her to join him for new year's prayers, she informed us. When she entered Abah's house, he had covered her mouth and informed her to lie down, she stated, before he stripped below the waist.

"He kept talking, saying he couldn't control himself any more, " Sukma remarked.

"He was feeling me up through my knickers. He tried to rape me."

And then, she remarked, she had identified the strength to kick him hard in the stomach and took the opportunity to flee.

As she ran, she remarked she had looked back to see his torch seeking her out.

As evidence like this emerged, Yusron would co-ordinate it – after up with calls to the students making the allegations, and keeping painstaking notes.

He typed up a seven-page document outlining the alleged abuse of Sukma, Zia and four other former students.

Wanda organised a session with representatives from the Nahdlatul Wathan Diniyah Islamiyah (NWDI) – the powerful organisation that ran their school and hundreds of others, and which was additionally funding some of the students' studies in Cairo.

Meanwhile, the session went well, the friends informed us – the NWDI representatives had noted they would assist them take the case to the police.

When Yusron received that ominous text from his sister – calling back to find Abah on the end of the phone in Yusron's family home – it became clear the NWDI had passed on Yusron's written documents to him, but three weeks afterwards.

"If this is leaked to the media. I'll be destroyed, " Abah can be heard saying on Yusron's recording of him.

He pleads with Yusron to lie for him, giving him a series of cover stories he can employ to retract his evidence document.

He then called Zia and exerted similar pressure. Like Yusron, she recorded the call. In it, Abah admits he abused her but pleads with her to stay silent.

Sukma, for her part, informed us she was called to Abah's house to discover two police officers and an NWDI lawyer waiting for her. They forced her to sign a document saying all her allegations were lies, she remarked. Her account is backed up by a secret recording she afterwards produced as she challenged Abah's wife, Hurmiati.

Hurmiati can be heard telling her to respect their "agreement" that nothing happened, adding: "Do you want this to haunt you for the rest of your life? Do you want it to damage the chances of you getting married?"

This pressure even extended to Abah asking Yusron's parents to fly to Jakarta to look for him at university. They didn't find him – he was hiding in a hotel – but the ordeal was too much for Yusron's mother. She informed her son the stress was killing her. So Yusron reluctantly halted his investigation.

Meanwhile he and Zia were gradually getting closer. The friendship had become a long-distance relationship, and they were regularly speaking on the phone.

"And I could see she was really struggling. She'd say things like: 'Why do I keep thinking regarding what did?'."

Yusron was torn between helping the girl he was falling in love with, and the promise he had created to his mother.

And then, eight months afterwards, Yusron heard concerning a group raising awareness regarding sexual abuse in Islamic schools. It had been set up by a young woman called Ayu Masruroh. This person had supported her friend secure justice after she had been sexually assaulted at another school, by a teacher called Moch Subchi Azal Tsani.

For now, our head teacher was an abuser. We joined forces to get justice remains the part of the story worth watching, and further updates are likely as more details are confirmed.