Fact: Bundles of twenty dollar bills found on Tena Bar were partially decomposed around the edges.
Experimental Fact: Experimental burial of bundled dollar bills in sand for 33 months showed almost no decomposition.
Interpretation: The Cooper money had been buried in the sand for an extended period of time to account for the observed level of decomposition.

Fact: Some of the Cooper bills were black from unknown causes.
Fact: Silver was detected everywhere on the black bills and a nitrate test came out positive.
Interpretation: Silver nitrate was used in an attempt to find fingerprints on the bills in 1980 but this was not recorded.

Introduction

In February 1980 the Ingram family was preparing to build a campfire along the Columbia River at a site called Tena Bar. While digging a fire pit, nine year old son Brian Ingram, uncovered three bundles of twenty dollar bills from the Cooper hijacking. This was the only evidence to turn up in the nine years since the skyjacking so the FBI combed the beach for evidence and experts were called in for further analysis.

The conclusions at that time formed the Washougal Washdown Theory that required the money to reach Tena Bar by natural causes. In the fall of 2008 when the Cooper Research Team was invited to examine the bills first hand, the general consensus was that since its discovery, there was no formal examination of the money. The goals of the research were to understand the way bundles of money were transported by water, the ability of rubber bands to survive in theelements,and determine how bills degrade in sandy environments.

Methods

Microscopic examination: Three Cooper bills were hand delivered by the FBI to the author's lab in Arizona for microscopic, elemental and molecular analysis. The bills were imaged front and back starting with a stereo microscope and ending with high-magnification electron microscopes. For comparison, several new one dollar bills that had been submerged in the Columbia River, were returned wet to the lab for examination.

Flotation analysis: A bundle of 100, new one dollar bills, was wrapped with a rubber band and set afloat in a tank with distilled water. Images were taken every minute to record the flotation progress. One bundle was placed gently on the surface of the water to float, the second was fully submerged instantaneously and then allowed to float freely.  

Silver nitrate test: Nitrate test strips were purchased commercially. They were dipped in distilled water and placed on both the blackened and normal Cooper bills. The color change indicated the strong presence of nitrates on the blackened bills.

Elemental analysis: Both electron microscopes used in this study utilized energy dispersive spectrometers (EDS) to determine the elemental compositions of the black coatings, the ink and other particles found on the bills.  IXRF and Genesis software were used to post-process and analyze the spectra. The majority of EDS spectra were recorded at 15 kVa, < 40% dead time.

Samples from Columbia River: Samples of sand were collected from Frenchman's Bar on the Columbia river a few miles upstream from Tena Bar. The sand was collected wet into sterilized jars for analysis back at the lab. Several one dollar bills were sealed in a sterile jar with one inch of river water to test for degradation.

Money burial test: A stack of nine new one dollar bills was cut into strips and partially buried vertically in the sand samples from Frenchman's Bar on 1-7-09. The jar was left sealed for 13 months after which the bills were removed and examined. The bill stack was replaced in the jar and a vent hole was added to the cap. The jar remained sealed for an additional 11 months at which time distilled water was added. Additional water was added again on 6-2-11 and 9-3-11. The bills were removed and examined for the amount of degradation over the 33 months they were buried.

Discussion

Microscopic examination showed that the Cooper bills were severely degraded at the edges and had holes in many places. The holes were examined closely to determine if they were insect boring's, root holes or bacterial colonies. Enough holes were present in various stages of decomposition that it could be determined that the holes were not clean cuts from insects, but appeared to start as a color change (Fig. 1A) progressing to shredding of the fibers (Fig. 1B), and finally to all the fibers in the hole disappearing (Fig. 1C). This is most consistent with a bacterial colony that is consuming the paper.

Immediately apparent on the blackened bills was a rainbow iridescence as shown in Figure 3. This signaled that there was likely a molecular layer on the surface causing light refraction.  Subsequent examination under EDS showed that the black coating was due to a silver on the bills surface. Several potential natural sources for the silver coating were examined, but in casual conversation, a law enforcement officer mentioned that silver nitrate that was used in the early 70's to detect fingerprints. This treatment had the negative side effect of eventually turning the evidence black. Commercially available nitrate test strips were employed and the results were clearly positive. Further examination of the news photos from 1971 did not show any black bills. Although there was no record of any testing done on the bills prior to this analysis, the data indicates the blackened bills were checked for fingerprints using silver nitrate at some point in the 70's.

The modern bills soaked in the Columbia River were examined using a scanning electron microscope (SEM.) At least three different species of fresh water diatoms were found immediately. Subsequent examination of the Cooper bills found no diatoms. Not seeing any diatoms on the Cooper bills does not guarantee that they are not there, so any final conclusions on this would be speculative.

The float test demonstrated that a bundle of bills will only float for a matter of minutes before submerging if there is any agitation in the water. Before sinking, the bills fan out as in Figure 4. Placing this in context with various theories, a rocky bottom stream like the Washougal River would provide continuous obstacles to bundles moving down stream along the bottom. The Columbia River has a sandy bottom which may allow movement of bundles when the flow rate is high enough. Bundles of money 'floating' on to a beach like Tena Bar has a low probability and would require strong enough water flow to push the bundles on to the beach.

As demonstrated in testing, the bundles of money fan out individually when under water, while a wet bundle out of the water tends to stick together like a brick. It is theorized that fanned out bundles should become mis-aligned while tumbling along the river bottom over time. While it is impossible to know at this time exactly how the bills were oriented, a clue comes from close examination of one particular Cooper bill. This bill had multiple  layers of fragments still adhered to each other at the edge. A closeup of this stacking is shown in Figure 5, and Figure 7 shows the reconstruction. At least three of the bills on top were displaced as shown, but the underlying stack was in relatively close alignment. While it could be argued that the top bills are displaced, the neat alignment of the lower stack would not be a likely result after 20 plus miles of river tumbling.

The remaining individual bills can also provide some idea of the stacks alignment during burial. Reviewing the available pictures, it is noted that the bills all degraded from the edges in and all in similar proportions around the entire bill. Had some bills been rotated out of alignment, they would have presented more surface area to the degradation processes in the sand and some corners would have been proportionally more deteriorated.  This is not apparent in the majority of the Cooper bills.

The money removed from the burial test after 33 months showed almost no degradation (Fig. 6). Damage to the edges was mostly shrinkage and contraction from drying out. This suggests the bills need a bio-active, oxygenated environment to induce bacterial breakdown of the paper. The environment in the jar would have been principally anoxic and did not mimic a natural sand burial.

Conclusions

The three bundles of 20 dollar bills found on Tena Bar in 1980 was the only evidence ever found after the hijacking. The simplest explanation that Cooper landed on or near Tena Bar would require that the published flight path was off by many miles, the jump timing would have to be off, and the pilots were not navigating in their normal manner via Victor Airway 23. There is currently no good data indicating that the flight path and timing of Cooper's jump were off enough to have him landing on or near Tena Bar.

The lines of investigation during this research could not pinpoint a natural means for moving the money from the woods near Arial Washington to the Columbia River. The rubber band testing outlined in other parts of this research place a constraint of about one year for the bills to become buried on Tena Bar. This places further restrictions on the speed that the bills would have to move by natural processes, further complicating any possible natural method of moving the bundles.

If natural means provides no plausible answer, then the other two possibilities are mechanical or human intervention. Of those two, mechanical methods are more problematic than human explanations. Since Coopers body was never found, if he did walk out of the woods following the jump, we can speculate that he must have had some human interaction that could have eventually led to the money being buried on Tena Bar. How the Cooper bundles came to be buried where they were remains as big a mystery as who D.B. Cooper was.