Cross-legged in a windowless, almost pitch-black bamboo shack, the investigator pressed record on a video camera and asked the young Rohingya woman to describe the night the Myanmar soldiers came.
"They broke down our door. They took my husband outside and shot him," recalled the 20-year-old, one of around 700,000 Rohingyas driven from Myanmar into Bangladesh a year ago.
"Then they killed my son. Four of them raped me," said the woman, who cannot be named for legal reasons, only her eyes visible beneath a veil covering her face, as the monsoon rain fell outside.
Different teams of investigators in the world's biggest refugee camp in Bangladesh, home to a million people, have been quietly documenting what the Myanmar Muslim minority suffered in 2017.
From seasoned professionals working for governments, the United Nations (UN) and international rights groups, to grassroots volunteers armed with pen and paper, a trove of evidence is being amassed which it is hoped will help bring the Rohingya some justice.
Another of those giving testimony is Nurjahan, whose husband and son were also murdered.
She has taken it upon herself to secure justice for them and for all the girls in her village raped at gunpoint.
She was among the first of 400 Rohingya women to put their inked thumbs to a legal document formally requesting a probe by the International Criminal Court (ICC).
The group of largely illiterate women she is part of, Shanti Mohila ("Peace Women"), has also collected victim testimonies and signatures to lobby the ICC thousands of miles away.
"We've lost our sons. Our daughters have been violated. We want justice for them," the 45-year-old said.
The only other Rohingya submission before the world's only permanent war crimes court is for the victims of Tula Toli, a Myanmar village whose Muslim inhabitants were rounded up and methodically slaughtered on 30 August, 2017.
Some testimony for a broader enquiry has already reached The Hague, where the ICC is being urged to investigate crimes against humanity, something that Myanmar denies.
There is a new Myanmar-led commission to examine abuses, but this has been denounced by many observers as an empty stunt that will fail to establish accountability.
A handful of soldiers have been charged by Myanmar for involvement in a single massacre but UN special rapporteur Yanghee Lee has tempered expectations that Myanmar's generals would stand trial anytime soon.
Myanmar is not a signatory to the court but ICC prosecutors and human rights lawyers have taken a unique approach by arguing that the crime of deportation was not complete until the Rohingya crossed into Bangladesh. And as Bangladesh is an ICC signatory, they say the court has jurisdiction.
A pre-trial chamber of ICC judges is reviewing the unprecedented request, alarming Myanmar which voiced "serious concern".
"They do feel some threat from this. I think that's important," said international lawyer Megan Hirst from Doughty Street Chambers in London, who is representing the Tula Toli villagers at the ICC.
How many babies?
Back at the camps in Bangladesh, another of those painstakingly pulling together evidence is Osman Jahangir, a field investigator from Bangladeshi rights watchdog Odhikar. His grim questions hint at the savagery of the violence.
"Where did the gasoline come from? How many soldiers raped you? Did you see how many babies were thrown in the river?" he asked refugees.
In a dark tent, Jahangir jotted down the coordinates of a Rohingya village on Google Earth. Where possible, he also gathers medical records and smartphone footage. In partnership with Hong Kong's Asian Legal Resource Centre, some of the findings were sent to the ICC. There are plans for a formal submission once rigorous field work is complete.
"I have studied the Bosnian war. There was a trial. They were held responsible," Jahangir explained. "I really hope we can bring justice to the Rohingya."
The NGOs and volunteer groups lack the resources and expertise of UN fact-finders or the United States (US) State Department, which sent veteran investigators to interview more than 1,000 refugees this year.
Justice experts also worry that amateur efforts to gather testimony risk contaminating evidence and undermining prosecutors in the event of a trial. But that does not dampen zeal in the camps.
"Nobody can deny this," said community leader Mohibullah as he scrolled through a database of abuses uploaded by Rohingya volunteers onto an ancient laptop, detailing gang rapes, torched mosques and murders.
Lawyers representing the Rohingya are quietly optimistic the ICC will decide it can investigate.
"But whether that means anybody will anytime soon end up in the dock, is a less optimistic prospect," said lawyer Wayne Jordash from Global Rights Compliance, who is representing the Shanti Mohila group.
On the other side of the world, in the squalid refugee camp, his clients say they are prepared for a long wait.
"We know this could take a very long time, years even. We don't care. We just want justice," said 25-year-old Sukutara, another Shanti Mohila member.
"Even if I die, and my children one day get justice, I will be happy." - AFP