Murder Mystery: When the Witness is a Tree

Could this wounded tree provide clues to what happened to Bonnie Woodward?

In late June of 2010 Bonnie Woodward went missing. An acquaintance, Roger Carroll, was an early suspect for her assumed murder but police found no evidence of any crime, and never found her body.  For nearly eight years she remained missing and the case went cold.  It was only after Roger Carroll admitted to his wife that he had killed Woodward that critical new information came to light.

 A witness claimed Carroll shot Woodward at his rural Jersey County, Illinois, home, burned her remains in a huge brush pile that he stoked for several days, then used a tractor to push all the evidence – or so he thought – into a creek. Carroll was taken into custody in April of 2018 and charged with first-degree murder.

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Front Page News! FPL's "Tree Detective" is Cover Story Material

Forest Products Laboratory (FPL) botanist Alex Wiedenhoeft has a fascinating career. Whether he’s using forensic botany to aid law enforcement, finding new ways to extract DNA from wood, or fact-checking certified wood products, he always has an interesting story to tell.

Isthmus, a weekly newspaper here in Madison, Wisconsin, agrees, and featured Wiedenhoeft and his work to curb illegal logging as this week’s cover story.


FPL botanist Alex Wiedenhoeft

If you thought illegal logging was just a problem affecting trees and forests, think again. The article explains that “when law enforcement agents capture a shipment of illegal timber, they also often find illegally captured wildlife, illegal drugs, weapons and slaves” and that “revenue from illegally harvested timber has been linked to armed conflicts around the world.”

To find out how Wiedenhoeft works to combat these disastrous consequences, and learn about some of the wild cases he’s worked on over the years, read the full article at

Looking for Better Wood DNA Extraction Techniques

Researchers at the Forest Products Laboratory (FPL) recently began a study focused on developing innovative techniques to extract quality DNA samples from wood and wood products.

According to an FPL Research In Progress report titled Anatomically Informed Optimization of Wood and Wood Products for Forensic Analysis, compared to other plant parts, wood is often a poor source of DNA, even if it is extracted from a living tree.  The processing of trees and wood can further diminish the quality and usability of that DNA.

A hickory specimen showing the heartwood–sapwood transi - tion and inner and outer bark. DNA content is highest in the  inner bark and lowest in the outer bark and heartwood. Inset: a  fluorescence micrograph of freezer-milled Alaska yellow-cedar  showing intact nuclei (blue-white dots). With organellar mi - crocapture, we will be able to selectively extract the nuclei for  analysis.

A hickory specimen showing the heartwood–sapwood transition and inner and outer bark. DNA content is highest in the inner bark and lowest in the outer bark and heartwood. Inset: a fluorescence micrograph of freezer-milled Alaska yellow-cedar showing intact nuclei (blue-white dots). With organellar microcapture, we will be able to selectively extract the nuclei for

Scientists hope exploring and developing improved DNA extraction practices will open the door to valuable, cost effective, and revolutionary research, especially in the field of forensic botany and timber forensics.

FPL researchers plan to examine various tree species in order to develop preprocessing methods for wood DNA extraction. Furthermore, botanists plan to explore the use of DNA databases and predict extraction protocols for new woods based on wood structure.

The project will conclude in 2018.

To learn more about this study, read the full Research In Progress report.

Blog post by Francesca Yracheta

All In a Day’s Work: Identifying Wood Species in Antique Horse Hames

Mike Wiemann, a botanist in the Forest Products Laboratory’s (FPL) Center for Wood Anatomy Research, has a special skill: identifying wood species, often with just a quick look through a tiny hand lens he carries in his pocket.

Mike Wiemann, FPL botanist, prepares a sample for identification.

Mike Wiemann, FPL botanist, prepares a sample for identification.

While most of us simply see wood, Wiemann can recognize varying species by looking at the end grain and evaluating the size and arrangement of the tissue components. And he did just that recently for a visitor to the Lab with a unique collection.

Willis Parker, a retired veterinarian, has an extensive collection of hames, two curved pieces of iron or wood forming (or attached to) the collar of a draft horse. Parker has collected nearly 400 hames over several decades, and is working to clean, photograph, identify wood species, and name the makers to preserve the history of their use.

Willis Parker shows Wiemann his hame collection.

Willis Parker (left) shows Wiemann his hame collection.

Interestingly, Wiemann happened to know what a hame was thanks to his college days. “In 1964, a requirement of the Intro to Forestry class I took my freshman year was to memorize and identify the parts of a harness,” said Wiemann. “I never thought I’d use that information again!”

With special permission from Wiemann (whose skills are in high demand), Parker brought 22 hames to FPL one sunny afternoon for wood identification. Some were well-worn and simple in design, used for work horses that pulled plows; others were painted and ornate, used when pulling carriages for wealthy passengers.

Parker laid out the pieces of wood, most dating from the early 1900s, and Wiemann got to work. What he found were hames made from ash, beech, red oak, white oak, hard maple, and elm.

Parker carefully tagged and labeled each hame after Wiemann announced the species, and he thanked Wiemann repeatedly for helping gather such useful information about his collection.

Wiemann was more than happy to help, as here at FPL, public service really is all in a day’s work.


Wiemann looks at a wood hame through his hand lens to identify the species.



Beneath the Bark : Tree Rings Tell Many Tales

We’re all familiar with the obvious changes northern-latitude trees go through as winter approaches, but did you know that there’s more to a tree’s seasonal changes than autumn’s brightly-colored foliage?

Researchers at the Forest Products Laboratory (FPL) study the both the external and internal structure of trees, and FPL’s Center for Wood Anatomy Research notes in the Wood Handbook that changing temperatures affect far more than the crimson and orange hues of fall.

When a tree grows, the wood is produced one layer of cell divisions at a time — but we do know from experience that in many woods, large groups of cells are produced at the same time, and these groups act together to serve the tree.

Transverse sections of woods showing types of growth rings. Ring development in softwoods ranges from no transition (A) to an abrupt transition between earlywood and late wood (C). Hardwoods (D-F) exhibit a similar range. The arrows delimit growth periods when present.

These collections of cells produced over the same time interval are known as growth increments. Because of the tree’s internal biological processes, these increments are arranged into layers. More commonly, these layers are referred to as growth rings.

In temperate portions of the world (and anywhere else with distinct, regular seasonality) trees form their wood in annual growth increments. All of the wood produced in one growing season is organized together into the recognizable, functional entity of the growth ring. In many tropical woods however, growth rings are not evident, as their climate zones lack seasonality.

Woods that form distinct growth rings, and this includes most woods that are likely to be used as engineering materials in North America, show three fundamental patterns within each growth ring: no change in cell pattern across the ring; a gradual reduction of the inner diameter of conducting elements from the earlywood to the latewood; and a sudden and distinct change in the inner diameter of the conducting elements across the ring.

The orientation of these rings can effect the tensile strength and elasticity of a wood product, and industry professionals must take this into consideration when deciding how a tree should be used.

In addition, most know that by counting the annual rings, researchers can determine the age of the tree, but analyzing growth rings can also tell us about the environmental conditions present when they were forming, including moisture levels in the soil and air, temperature, and sunlight.

In larger trees, annual rings can represent decades, if not centuries, of growth.

Abnormal rings can also be linked to traumatic events in the tree’s past, like forest fires, disease, or climate events, and the rings become not only a record of the life of the individual tree, but of the forest and environment as a whole. Many other disciplines, like archaeology, can use this information (known as dendrochronology) to support their own research, making wood one of the best record keepers on the planet.

For more information, please see Chapter 3 of The Wood Handbook, Wood as an Engineering Material.