The following is an excerpt from Forest Products Laboratory 1910 – 2010 : Celebrating a Century of Accomplishments.
Wood science is not always about designing ingenious experiments or cutting-edge inventions. Over the years, researchers at the Forest Products Laboratory (FPL) have been called upon to use their expertise to help other agencies. Sometimes, this amounts to nothing more than uncovering decayed trees in a local city park, but in this case, it meant helping to convict a killer on the other side of the country.
In the “Case of the Red Paint Chip,” a murder had taken place in Georgia. The victim was found in the woods covered with debris, including chairs, rugs, cushions and two red painted posts. This area was used by hunters, who apparently brought the items and left them there.
The red posts, however, were thought to belong to the suspect, the husband of the victim. The victim’s son confirmed that red posts were stored in the house and that he had seen them in his father’s pickup truck.
In the victims house, under the stairs where the red posts had been stored, a red paint chip was found on a piece of yellow pine. This red paint was compared with the red paint on the posts, and a good match was noted in gross structure and chemical analysis. The forensic scientist in charge noted that there were a few fibers clinging to the back of the red paint chips.
Regis Miller, from the Center for Wood Anatomy Research at FPL, was asked to examine these fibers to determine whether they were conifer fibers from the yellow pine lumber, or fibers from the red painted posts, which were identified as from a species in the white oak group.
Sample and magnified view of the paint chip found on a pine board in the basement of the accused murderer’s home.
The ray cells did not have any cross-field pitting and no ray tracheids were evident, suggesting that they were hardwood ray cells and not rays from a conifer. These fibers were of two types: pointed thick-wall fibers and long, broad, thin-walled fibers. Fibers of two distinct types do not occur in the conifers, but they do occur in some hardwoods.
Miller concluded that the fibers were libriform fibers and vasicentric trachids that are typical of oak. Under high magnification and polarized light, the fibers from the red paint chip appeared to have large slit-like structures that initially were thought to be pits. Upon closer scrutiny, however, these slit-like structures were found to be the openings caused by decay fungi.
This decay pattern was found both in the fibers clinging to the red paint chip and the white oak posts. Not only were the decay patterns the same, they came from the same type of fungus. This case used both identification and comparative anatomy to show that the red paint chip found in the house did come from the red painted posts found at the scene of the crime.
Miller concluded that the, “analysis of the fibers attached to the paint chip indicated that the paint was from some hardwood posts that were found with the victim’s body and had been stored in the basement of the accused murderers home, and not from the pine 2×4. The paint was evidently chipped off when the posts were moved from the basement and used to help cover the victim’s body.”