I wasn’t imagining they were actually locked up in the factory, but after reading one of the linked articles from the original article:

“On 28 February, the Vietnamese man escaped the facility by climbing up a wall, crossing a river, and seeking refuge at a farm. The farm owner then reported it to the police. There were signs of torture on the man, including scars and marks from electrocution, said Mr Casio, whose team visited the man early this month.”

that seems to be the case.