Behind a high-security fence at a secret bushland location outside of Sydney lies one of the only body farms in the world, where scientists are studying the various ways human corpses decompose.

Lateline has been given exclusive access to the body farm, which is the only facility of its type outside of the United States.

It is officially known as the Australian Facility for Taphonomic Experimental Research, and Shari Forbes, dubbed Australia's Queen of the Dead, is one of its few living inhabitants.

WARNING: This article contains images of animal remains.

There are currently 19 bodies at the facility in various burial scenarios.

"Nine of those are above ground in what we would call a surface deposition and 10 of those are below ground," Dr Forbes told Lateline.

"We have several graves. One is a shallow grave to mimic a typical forensic scenario and the other two are deeper and involve multiple bodies and those would represent a mass grave scenario."

A pig carcass: scientists use pigs because internally they are similar to humans. ( ABC TV )

Dr Forbes says they are trying to determine whether bodies decompose differently when they are bunched together in a mass grave.

"We only ever know the outcome when our archaeologists are involved in human rights investigations excavating mass graves and so we know what we see at the end but we don't really have a good understanding of the differential decomposition — the fact that some bodies can be preserved and some can skeletonise in the same environment," she said.

The scientists have also been collecting decomposition odour to help train cadaver dogs.

In order to do this, an aluminium hood is placed over a body and the odour is pumped into a tube for analysis.

Dr Forbes says a mass spectrometer — worth about $250,000 — can identify the chemicals in the odour, but even the high-tech machine cannot compete with specially trained dogs.

"[The machine] can detect about one part per trillion, which would be about a teaspoon of sugar in two Olympic-sized pools, so that's really pretty good but it doesn't really compare to the dogs," she said.

"The dogs could do about one teaspoon of sugar in more like six Olympic-sized pools. So their sensitivity is far superior to any of the instruments we have."

Man's best friend versus machine: Bronte the cadaver dog and a mass spectrometer. ( ABC News: Brant Cumming/Matt Wordsworth )

At the nearby animal body farm, Dr Forbes and her team are using pig carcasses to help in real-life crime scene investigations.

Some of the carcasses have been burnt — some with petrol and some without — to test how long fire detection dogs can smell accelerant when investigating arson.

PhD student Maiken Ueland says pigs make perfect substitutes for human bodies in these kinds of experiments.

"There's a lot of legal and ethical restrictions with the use of humans so we use pigs as analogues because they have the same internal anatomy and they lack heavy fur," she said.

In another experiment, Ms Ueland dressed the pigs in clothes to see how long the textiles took to break down. She said they found that the decomposing body actually helped to preserve the clothing.

"I think it's the fats, so the lipids in the decomposition fluid, it sort of lays on top of the material and creates a seal," she said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 9 minutes 56 seconds 9 m An exclusive look inside Australia's human body farm

More than 300 people have already offered to donate their bodies to further research at the farm.

Within 24 hours of a donor's death, their body will be taken to the mortuary at the University of Technology Sydney.

Twelve hours later they will be on the body farm, where Dr Forbes says they will be contributing to some world-leading research.

"We're forever indebted to the donors and to their families," she said.

"We understand that it's an unusual way to donate your body to science, perhaps even more so than medical schools, so we are truly grateful of the contribution they make to our science."