There were 984 people held in Australian immigration detention at the end of September. More than 800 detainees have a criminal record and just over 100 are people who arrived unlawfully by boat.
An investigation by this masthead last year interviewed dozens of current and former Serco guards and detainees, many of whom claimed understaffing was entrenched, leading to violence, allegations of sexual assault and an illegal drug trade that puts both detainees and staff at risk.