They can’t scream “whodunnit” but plants can provide vital clues when it comes to finding secret graves, the researchers say.

Forensic experts in the United States have begun experiments at a cadaver farm – a facility where decomposition processes can be studied – to explore whether decaying human remains leave their imprint on surrounding plants, for example by affecting leaf color.

If successful, the team says this approach could aid efforts to find and recover bodies.

“There should be spectral changes occurring in foliage, and we should be able to see them,” said Neil Stewart, a professor of plant science at the University of Tennessee and one of the authors of a proposed approach. .

Writing in the journal Trends in Plant ScienceStewart and colleagues note that in the United States alone, 100,000 people are lost each year. They say hunting forests on foot is especially challenging, and foliage can hinder remote sensing of landmarks on the ground.

However, the team says the plants themselves may provide clues, and if so, they could be detected from above using sensors on drones.

The key, they say, is that microbes and chemicals associated with decomposing bodies, known as necrobiome, alter the surrounding environment. The team observed that the average human body contains about 2.6 kilograms of nitrogen.

“[With a] Large nitrogen flush, plants will respond by producing more chlorophyll – at least, that’s our expectation. But it may stress some tree or shrub species until they lose their leaves or change color, either to yellow or red, “said Stewart.

Stewart said such effects should be detectable by measuring the properties of the light absorbed by the leaves, and may appear within days, with the expectation that invasive plants or weeds will be the first to respond.

The team plans to start unmanned flights over the mortuary this month. They also plan to take laboratory measurements to see if plants exposed to decaying bodies show changes in their radiance.

Dawnie Steadman, a professor of anthropology at the University of Tennessee, told The Guardian that the team put early donors in the woods around the facility in August. “We have so far placed three donors,” she said, adding that the bodies would be left for up to a year.

Stewart said basic data on soil composition, plant species and light absorption by foliage has already been collected. “We have to define the changes [in the plants] First before we can figure out how special it is to humans rather than something like a deer or wild boar. “

He said that humans may leave distinct traces. “[Humans have] Long life as different compounds can accumulate in their bodies. ”The team says the cadmium from smoking may be one of those signs.

It might even be possible, Stewart said, to use the approach to identify specific people. “It is actually not far-fetched because everyone may already have some indicators, if you know what those indicators are,” he said.

Dr Chris Rogers, a lecturer in forensic science at the University of Wolverhampton, who was not involved in the project, said that while there was a lot of work to be done to determine whether the proposed approach could work in forensic contexts, in theory it seemed Is possible.

“Any technologies that can help speed up finding areas of interest or exclude areas from searches are very welcome,” he said. “What the authors have suggested here is remarkable.”