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.

Transfield: runs Nauru and will soon run Manus Island

The large Sydney-based construction firm has just confirmed a $1.22 billion Australian government contract to run the centres on Nauru and Manus Island for 20 months. It will provide “garrison and welfare services” but not medical and counselling services, and it will contract out security to Wilson Security. Last February it was awarded a $175 million contract to run Nauru.

You might have seen Transfield at work in mining or property. Providing welfare at an asylum seeker camp is somewhat outside its normal sphere of activities, which is why there’s been a call for a boycott of the Sydney Biennale (Transfield is a major sponsor).

To put the immigration contract in proportion, Transfield’s revenue in 2012-13 was $3.45 billion and profit (after tax and impairment) $250 million. So the Manus/Nauru deal is worth much more than building mining equipment for Twiggy Forrest.

The company employs 24,000 people in 11 countries, but much of its work remains in Australia, and it’s listed on the ASX. It works in the United States but is scaling back in Asia. It mostly works in construction and asset management in resources, energy, industry, property and defence. It’s doing a lot on coal seam gas in Queensland — installing wells and rigs — and works in iron ore, oil and gas (for Rio Tinto, Boral, Woodside, etc). Transfield has a $366 million contract with NBN Co, works for local councils and the Defence Department, and is involved in railway upgrades and Sydney’s ferries. Transfield has a long list of local subsidiaries: Broadspectrum, Easternwell and HRI.

Until recently the Transfield chairman was Coalition favourite Tony Shepherd. He retired in October but remains president of the Business Council of Australia and is heading up Tony Abbott’s Commission of Audit. The company has had some corporate governance issues due partly to a breakdown between the two families who set it up.

Serco: runs Christmas Island and onshore immigration detention centres

This UK behemoth provides all kinds of services around the world. Among them it runs the Christmas Island immigration centre (which is part of Australia) and onshore centres including Villawood in New South Wales, Curtin in Western Australia and the Darwin Airport Lodge. Note that the contract to do this expires late this year. Last year there were claims Serco had disciplined four staff on Christmas Island for having sex with detainees or drinking alcohol.

Serco is based in the United Kingdom — just over half its revenue is from Europe — although it’s active in the US and Asia. It employs more than 100,000 people in 30 countries. It’s a nebulous company, providing catch-all “services” to governments and private companies in many ways.

A key area is the military. Serco manages Britain’s Atomic Weapons Establishment — which develops “the sophisticated materials, quantum physics and computer modelling vital to the safe and effective maintenance of the UK’s nuclear deterrent” — with Lockheed Martin and Jacobs. Serco also maintains the UK’s anti-ballistic missile warning system and its Skynet 5 military satellite communications network. The list of US Defence work that Serco does is both long and unrevealing.

Globally, Serco also works in prisons, trains, pathology, air traffic services and UK “welfare to work” programs.

So what does it do in Australia? As well as immigration detention, it works in court security, call centres, defence (some work is via DMS Maritime and JV Serco Sodexo Services) and Victoria’s speed cameras. It’s providing services at Perth’s new Fiona Stanley Hospital for the next decade. Serco owns Great Southern Rail, including the Ghan link.

Things were going well for Serco in 2012 — global revenue of 4.9 billion pounds, adjusted operating profit of 314.8 million pounds — then, like G4S, trouble struck over e-monitoring of prisoners. Serco was accused of overcharging the UK government, had to repay 68.5 million pounds, and was subject to a critical government review and more allegations of poor performance. The UK government’s Serious Fraud Office is investigating. Serco was banned from bidding for UK public sector work until this month, the Financial Times reports. The CEO resigned in October and in January Serco issued a profit warning.