When asylum seekers like Reza Berati try to come to Australia by boat, they are not only sent to remote islands, they're sent to detention centres that have been outsourced to massive global companies. The three firms that run these centres have a vast reach and are involved in everything from nuclear weapons to coal seam gas and "investigative services". Two are under investigation for serious fraud. So when 23-year-old Berati died of a head injury inside PNG's Manus Island camp a week ago, amid contested allegations that the camp's security guards were involved in a riot, it's hard to get answers from the Australian government. It does not run the camp and it does not employ the guards. A British security firm called G4S does. The federal government sends all unauthorised boat arrivals offshore; thousands are in the camps now. So who are the firms running Australia's detention centres? Here's a guide to G4S, Serco and Transfield -- which between them have their fingers in some very interesting pies ... G4S: runs Manus Island camp in PNG but will soon be gone

The London-based security giant had a $244.5 million contract from the Australian government to run the Manus Island camp ("operational and maintenance services"). It lost the contract a few months ago and will formally handover to Transfield in early March. G4S was in charge of the camp when Berati died, and has defended its staff and promised to co-operate with the government's investigation. G4S employs almost 625,000 people in 125 countries. Almost half its revenue still comes from Europe, but it's active right through America, Asia and Australia. The company's slogan is "securing your world", and its bread and butter is security-related services for governments and private companies. It provides guards, watches over ATMs, and works in prisons, court escort and data protection. It's a risky business; 18 staff died from "attacks" in 2012. In Australia, G4S runs Victoria's Port Philip Prison and provides patient transport for the state Health Department. The company does prisoner transport in Victoria and South Australia, and it runs electronic monitoring of offenders (more on that later) in SA. G4S operates "guarding and security services ... in every Australian state and territory". It guards everything from hospitals to control rooms and major events. G4S also conducts "investigative services" --  snooping for insurance companies and government organisations. The company has done some work in PNG under the name G4S Secure Solutions (PNG) Ltd, e.g. "manned security" for the UN (see the 2012 annual report). G4S' figures for 2012 looked all right -- global group turnover of 7.3 billion pounds for the calendar year and profit (before tax) of 516 million pounds -- then trouble struck. The firm was placed under a criminal fraud investigation for overcharging the UK government for the cost of e-monitoring offenders. The CEO resigned last May. Previously, G4S made headlines for stuffing up security at the 2012 London Olympics (the army had to be called in). G4S has been criticised for its management of Manus Island, and not just over Berati's death. Just yesterday the ABC claimed the company had hired a former Sri Lankan military officer as acting camp manager.