A police spokesperson in Indonesia's Papua says criminal charges will be laid against a mine company if negligence is found to be the cause of the tunnel collapse that killed 28 workers this month.
According to the Jakarta Post, Senior Commissioner Gede Sumerta Jaya says they have interviewed 12 witnesses, including mine owners Freeport McMoRan and the survivors of the incident.
Investigations are underway at the mine, and Mr Sumerta Jaya says based on preliminary investigation, the collapse seems to be due to natural factors, such as cracks caused by erosion in the limestone of the tunnel's ceiling.
The newspaper reports workers have returned to the mine to check equipment but there has been no production yet.
In 2009, a worker died and four others were injured in another mine collapse and in 2008, at least 20 miners were buried when the mine's tailings heap collapsed on them after two days of heavy rain.