Napier. Rakaia Gorge. Avon River.
If he was going to solve Mellory Manning’s
murder, the pollen detective needed to
exorcise his ghosts.
Part Three
By David Wolman
Illustrations by Cam Floyd
The basic forensic approach used at crime scenes today centers on Locard’s exchange principle: When any two things come into contact, there’s always some transfer of material, whether it’s tire tread on a pavement, bodily fluid on a bedsheet, or a jacket placed in a tree. Perpetrators and victims always transport objects with them to a crime scene, take things with them when they leave, and likewise leave things behind.
Some types of trace evidence — bodily fluids, clothing fibers — are used regularly in criminal investigations. But pollen, despite the fact that it exists almost everywhere, has been adopted more slowly.
In the late 1950s, it was used successfully in a murder case in Austria, where the police had a suspect and a motive but no way to link the man to the crime. The break came when investigators took a pair of muddy boots from the suspect’s home and sent them to a renowned geologist, who found pollen from willow, alder, and spruce, as well as rare hickory. Only a small sliver of land in Austria had soils characterized by this particular pollen brew, and when the suspect was told that police had evidence of where he had walked — and mentioned this specific area — the man sang his confession.
In the decades that followed, pollen analysis was used in cases here and there, but for the most part forensic palynology simply wasn’t, and isn’t, a thing anyone has heard of. One limiting factor is that just a handful of people on the planet can bring to bear the necessary analytical acumen. “There are only about 350,000 different pollen grains. It takes some skill to differentiate them,” quips Vaughn Bryant, professor and director of the palynology lab at Texas A&M University.
As a kid growing up in the hilly rain forests of New Zealand’s North Island, Mildenhall often went exploring in the woods or ventured into abandoned gold mines or made his way deep into the mountains, listening to the calls of native birds. From an early age, he loved the taxonomic.
At university, he studied geology because it seemed like the easiest way to bring his studies outdoors. His knack for mental cataloging made a palynology specialty a natural fit, and soon after graduation he took a job as a staff scientist with GNS. At the time, he spent most days looking at fossilized pollen from ancient forests.
One day in 1973, local detectives asked one of Mildenhall’s colleagues to look at some soil samples. “I thought, Oh — I can use palynology for this!” He conducted an analysis, but nothing remarkable came of it.
His first big case was in 1983. A fourteen-year-old girl named Kirsa Jensen had taken her horse, Commodore, for a ride along the beach near the town of Napier, on the North Island. The horse was later found wandering by a nearby river, but Kirsa had vanished.
She had been riding near an historic gun emplacement, built during World War II in case the Japanese decided to invade New Zealand. Mildenhall used pollen analysis to determine that a rope found at the site had substantial concentrations of pumpkin, beech, and broad bean pollen grains. Mildenhall then showed that this pollen profile matched a second rope, found on the farm where the primary suspect was employed.
Until then, most of Mildenhall’s forensic work had taken place in the lab, with samples sent back and forth in the mail. For the Jensen investigation, however, he became deeply involved, visiting the site along the beach, collecting samples, mapping vegetation, and examining photographs. It was detective work, minus the badge. “I just got so emotionally invested in it,” he says.
The police and the Jensen family were hopeful that this barely known forensic technique would strengthen the case. But in the end, the court concluded that prosecutors still lacked enough evidence. The family was devastated, and the suspect later committed suicide. “They will never have closure,” Mildenhall says.
Fifteen years later, a fifteen-year-old girl named Kirsty Bentley took her Labrador for a walk not far from Christchurch and didn’t return home. Kirsty’s body was later found in Rakaia Gorge, some fifty miles north. “I can still see her feet poking out from under the shrubs that had been placed on top of her,” Mildenhall says. How did she get to the gorge? Who took her there? “Nothing on her shoes, clothing, or anything gave us anything beyond what we knew,” Mildenhall says.
Bentley’s murder was never solved, either. Mildenhall says those two cases still haunt him. Certain words bring emotions and memories bolting to the forefront of his mind. The triggers can be anything, but often they are place names or pivotal details. Napier, Rakaia Gorge, rope. “Anything like that brings back the frustration about the cases.”
Greg Williams, the detective heading up the Mellory Manning investigation, had worked with Mildenhall on the Bentley murder. Even though the earlier case remained unsolved, Williams was still bullish on forensics. Almost as soon as he started trying to find Mellory’s murderer, he had investigators relaying pollen samples to Mildenhall to see what he could find.
The first sample was extracted from Mellory’s nasal passages. As we breathe, our respiratory systems capture pollen grains, which get cycled in and out of our noses about every twenty minutes. These grains persist in the body long after death, and Mildenhall found small quantities of pollen from grass, birch, and tree fern in the sample. If a victim is facedown on the ground just before death, hundreds, if not thousands, of grains will typically be found in nasal samples. The relative dearth of samples from Mellory suggested that she had been on her back at the time of the fatal attack. This was potentially useful for understanding the murder itself, but it did little to help the police figure out where she had been killed.
Mildenhall received sample after sample to compare with the material from Mellory’s body and clothing. It was slow going, and after a period of more than a year, he had helped the police eliminate dozens of possible murder locations.
But as the months passed without an arrest, Mildenhall began to feel as though he was reading a depressingly familiar script. He’d helped the authorities win convictions in cases all over the globe, yet every time a young woman was murdered at home in New Zealand, the world’s most talented pollen sleuth couldn’t do a damn thing. He grew increasingly pessimistic. Was Mellory’s case destined to go the same way as that of Kirsa Jensen and Kirsty Bentley? Napier. Rakaia Gorge. Rope. Avon River.
One sample, at least, held some promise — even if it wasn’t conclusive.
“In my opinion, the evidence does not support the contention that Manning took her last breaths at the sites represented by the comparator soil and vegetation samples from Dallington Terrace, Avon River bank, Caledonian Hotel carpark, or 26 Gresford Street,” Mildenhall wrote in a report to the Christchurch police. However, “The evidence does not exclude the possibility that Manning took her last breaths at 25 Galbraith Avenue.”
It was the address of the Mongrel Mob’s pad.
Read the final part now.
David Wolman’s The Pollen Detective is a murder mystery in four parts.
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