A former headmaster of an Islamic boarding school in Indonesia has been named as a suspect in a sexual abuse investigation and detained by police, following a BBC Eye report.

Ahmad Imanuddin Sumar, known to students as Abah, led the Abul Barokat boarding school on the island of Lombok.

Police reopened the case after the BBC World Service revealed accusations of sexual abuse against him, and documented how former students had gathered evidence in an effort to bring the allegations to the authorities.

The story sparked public outrage and led to 12 more former students giving testimony to police.

Warning: This story contains details of sexual assault

Two ex-students expose sexual abuse by teachers at Islamic boarding schools in Indonesia

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Central to the BBC Eye investigation were former students Ziadatur Rahmah, known as Zia, and Sukma Rohana Fajar.

They launched their own investigation after Zia told a former classmate, Yusron Azzahidi, that the headteacher had sexually assaulted her when she was 17. The pair had been star pupils at the school.

By the time Zia confided in Yusron, she was studying in Cairo, Egypt, while he was in Jakarta.

Yusron suggested they gather evidence to support Zia's allegation. Speaking to former classmates, they spoke to Sukma, who alleges that Abah attempted to rape her at the school.

Yusron compiled a seven-page document detailing the allegations, and they gave it to representatives of Nahdlatul Wathan Diniyah Islamiyah (NWDI), the organisation that ran the school.

Thinking the school would support them, the students say that instead, they were pressured to withdraw their accusations.

In a secretly recorded phone call, Abah pleaded with Yusron to protect him and his reputation.

"Cover the shame of your teacher. Everyone makes mistakes, my child," Abah said.

Abah also contacted Zia, who secretly recorded their conversation and shared it with the BBC.

In the recording, Abah is heard apologising, but pleads with her to remain silent.

Following the BBC investigation, Abah held a news conference where he denied all the allegations. He did not deny that the voice heard in the recorded calls was his, but said the recordings were not confessions.

Sukma told the BBC she had been forced to sign a document saying her allegations were lies. She later secretly recorded a conversation with Abah's wife, known to students as Umi. In the recording, Umi tells Sukma that the document was intended to protect "her good name".

The former students eventually resumed their efforts to seek justice, with support from lawyer Joko Jumadi, who has experience in similar cases.

The day after the BBC investigation was published, parents arrived at the school to collect their children, with some travelling from other islands.

One mother said she had begun crying when she heard the news, thinking about her daughter.

"I'm moving her right now," she said. "I absolutely want my child to leave this school."

Yusron said he and Zia, who recently got married, were overwhelmed by the response from former students.

"It was beyond what we expected," he said. "So many people contacted us - on Instagram, WhatsApp. They contacted me and Zia directly, and lots of them were saying, 'I'm a victim too'."

Police interviewed Zia and Sukma, along with the 12 other former students who came forward with allegations of abuse.

"They thought they were the only ones - and it's been really shocking for them to learn, like I did, that they weren't alone," Zia said.

Sukma said she felt relieved and grateful that the allegations are now being taken seriously.

"It's not about revenge. It's more the acknowledgement that what he did was wrong. I'm waiting for the day when he admits that himself," she told the BBC.

Abah has resigned from the school and has said he will respect the legal process.

NWDI denied trying to cover up the allegations and said it was investigating them internally. It said it had a duty to protect the organisation from being tarnished by the alleged actions of individuals.

In the wake of the BBC investigation, NWDI vowed to ensure such abuse never happened again and said it would safeguard the rights of students who came forward.