Botanist tells how nettles helped solve Soham murders

Botanist Patricia Wiltshire has revealed how her knowledge of stinging nettles helped police solve the Soham murders in 2002 – a case which concluded in the conviction and a life sentence for school caretaker Ian Huntley.

Wiltshire, who is a palynologist – a pollen expert – was speaking to Lauren Laverne on Sunday’s episode of BBC Radio 4’s Desert Island Discs. S he discussed her early life in a Welsh mining village, her lifelong love of nature, and the secrets that plants can reveal.

Raised in a small village north of Cardiff by two “volatile” parents, Wiltshire spent a lot of time with her grandmother, Vera May: “She understood the hedgerows, she understood plants and animals, she showed me birds’ nests and so on.”

Wiltshire came to her botany degree a little later in life, after leaving school halfway through her A-levels. When she discovered the subject and her interest, she said: “I found my niche at last.”

There are two ways that Wiltshire uses her botany expertise to solve crimes. In some cases, she explained, a small piece of evidence, such as a trace of pollen, can lead to the type of plants that were in the area, which can help you work out the climate and geology, and start eliminating places where the crime took place.

“Very often, when you’re looking for bodies for example, I’ll say to the police, ‘It’s this sort of place, but it’s in the north of England.’ Then the local ecologist will say, ‘I know a place like that.’”

In other cases, Wiltshire will observe the scene for clues. “The perpetrator, someone who has committed a crime, has left their mark on that place and it may be very, very subtle, so you’re looking for little impressions – impressions in leaves, little broken twigs,” she told Laverne.

In 2002, the bodies of schoolgirls Holly Wells and Jessica Chapman had been discovered in a ditch, and Wiltshire was brought in to establish the path taken by the murderer. The ditch was covered with stinging nettles and other vegetation, and police could see no obvious way in.

“It was decided that when the girls were found, I would be first into the ditch, because I’d be looking for these little clues,” she recalled. “The nettles were chest high.”

Wiltshire noticed stinging nettles that appeared to have been trodden on, then regrown since the murderer had been there. The disruption in the nettles’ growth allowed her to deduce exactly how long it had been since the girls’ bodies had been left there. “I keep nettles in the garden for butterflies. I looked at the little side shoots – I thought, ‘This has taken about two weeks to grow.’”

She was also able to show police exactly where Huntley entered the ditch, allowing them to search the path for clues. “I found Jessica’s hair on a twig,” she told Laverne.

“There is a satisfaction that you’ve solved a puzzle,” she said, but some cases have stayed with her. In the case of Michelle Bettles , who was found in Norfolk woodland but whose murderer was never brought to justice, “poor Michelle did affect me,” Wiltshire said.

Wiltshire has experienced loss herself – her young daughter Sian died while only a toddler. “I never have coped, really,” she said. “I don’t think you cope with the loss of a child. Even after all these years, she’s there every day. I don’t have words, they’re all feelings. It does get easier over time, but it never goes away.”

She said the experience has helped her empathise with the families involved in the cases she helps investigate. “I always feel for the mothers and the fathers. This work has given me a great measure of compassion.”

• This article was amended on 30 June 2024. Ian Huntley was a school caretaker, but not at the school attended by Holly Wells and Jessica Chapman as an earlier version implied.