The defense side of the Casey Anthony murder trial has invested many frames of media to emphasizing the “difference” between the four pieces of duct tape found at the crime scene and the piece of duct tape found on George’s old metal gas can. Let’s be clear the “defense team” doesn’t just include Casey and her entourage of lawyers, it also includes Cindy, George, Lee and Brad Conway, Cindy and George’s lawyer. Brad continues to state he doesn’t work for the defense, only for Cindy and George, but his actions continue to reflect a far different reality. Brad went so far as to hold a press conference, immediately before the discovery release of the forensics on the crime scene duct tape pieces, announcing those pieces of duct tape did not come from the same roll of duct tape as that piece on the gas can because they were “microscopically different”. Immediately after the discovery release the three-person defense team of Jose, Linda and Todd hit the news program circuit and centered their focus on issues of “duct tape”.
These “issues” focus on three things:
* The forensic results of the cloth comparison between the four pieces of duct tape at the crime scene and that of the duct tape on the gas can.
* DNA that was present on one piece of duct tape removed from Caylee’s skull that had foreign DNA – ultimately found to be that of an FBI employee.
* An allele, found in DNA testing of the pieces of duct tape at the crime scene, which neither Casey nor Caylee possess in their DNA.
So let’s look at these one at a time.
First, let’s talk about duct tape in general. As illustrated on this Duck Tape University site, and illustrated below, any brand of duct tape is constructed in three layers fused together by pressure and heat. These three layers are the polyethylene backing (usually gray), the cloth (which gives the tape it’s “strength, and makes it real damned hard to tear), and the adhesive.
A really good youtube video is below that walks you through the manufacturing process for duct tape. No matter what brand of duct tape you want to talk about, this manufacturing process will be similar to what you see in this video.
It’s actually preferable that you take the time to watch that video because there’s some things I’d like to point out right now that will play into analyzing certain defense claims later. The first thing is, take careful notice of just how many rolls are made in one “production run”. A production run consists of those huge rolls of cotton cloth and polyethylene backing being consumed into one huge roll (the mother of all rolls!) of duct tape. That duct tape is then “unrolled” into smaller, consumer-sized, rolls that are then packaged and shipped out to retail stores. So the important point here is that for two rolls of duct tape to be from two different production runs from the same manufacturing shop would require one of two things:
1. You purchased them from two different stores around the same time, but one store was stocked by production run X and the second store stocked by production run Y.
2. You purchased them at the same store, but a good period of time passed so that when you went and got the second roll, a new production run had been shipped to the store.
Now, for scenario 2, the time that would have to pass before a single production run of duct tape was consumed and the same store received from a new run would be dependent on how popular (i.e. how quickly) the brand of duct tape in question was being consumed. So if Brand X constitutes 50% of the duct tape market, it might not be but a month before a new production run was hitting the same store. But if Brand Y is, say, less than 1.0% of the market, it might take months to a whole year before the same store received duct tape from a new production run.
Henkel Brand Fire Resistant Duck Tape, the duct tape found both at the crime scene and on the gas can, constitutes less than 1% of the total U.S. duct tape market. And the reason this statistic is important in the case is that it greatly decreases the probability that the five pieces in question came from different rolls, let alone different production runs. After all, unless you are in the business of making the current trendy “duct tape clothing”, and you’ve decided to make that clothing out of less than fashionable gray duct tape with oval black Henkel branding on it, you’re probably not going to run through a roll of duct tape in a year’s time. I live in a 105 year old home that I’m constantly in the process of remodeling and we use duct tape to seal off areas that are under construction, so we use above and beyond the normal consumer. We’ve only had to buy a new roll of duct tape every couple of years at our higher rate of usage. Add to this that Henkel stopped making this brand of duct tape in 2007, and you’re left with…these duct tape pieces (all attached to the Anthonys via Caylee’s remains and George’s gas can) had to have come from either the same roll of tape, or a possible multi-pack of duct tape that (as can be seen in the video) would have come from the same production run.
But let’s pretend, as the devil’s advocate, that they came from different production runs. What difference would that make? Only variations acceptable within the specs (as we will discuss), but not the difference noted in the forensics. First we need to look at what the “microscopic difference” is between the duct tape pieces found at the crime scene, and the piece found on the gas can. It is reduced to the following six lines of Quantico analysis notes found on page 627 of this released discovery:
Notice in Q66 (duct tape from George’s gas can) that the double asterisk observation “off-white cotton” is not present in the analysis of Q64 (one of the pieces of duct tape that was on Caylee’s skull). This, and this alone, is the difference between the four pieces of duct tape found at the crime scene and the piece on the gas can. And to emphasize that this is the only difference, we review the analysis of all other aspects of the comparison of the crime scene duct tape to that found on the gas can on pages 67 and 68 of this released discovery:
Please note that after analysis of the adhesive and the backing, the laboratory analyst’s conclusion was that they either were from the same roll, or from the same manufacturing process. So the question becomes, did Henkel use different manufacturing processes to make their Fire resistant duck tape? Well, the answer is no. And it is born out by reviewing the product specifications provided to law enforcement by Henkel upon subpoena. You can read those specifications in this released discovery. Now for those not used to dealing in product specifications used by a manufacturer, a bit of explanation may be needed at this time. A product specification is how a manufacturer of an end product (say duct tape for purchase at your local Lowe’s) controls the quality of both the raw materials that go into the production of that product, as well as the quality of the final product before allowing it to ship out for consumption. When the raw materials come in from the manufacturer’s supplier (i.e. in this case the cloth, the adhesive (including the separate products that are mixed to make the adhesive), and the backing) a quality control check is done to ensure that raw material meets the specifications Henkel has put out. If a raw material falls out of an acceptable variance on those specifications, it will be returned to the supplier (i.e. rejected). The same holds true for the final product. If, say, a random sample of a production run of duct tape didn’t meet tensile requirements, or some other required parameter, the entire lot may need to have additional testing done or be rejected due to poor quality.
That’s important because when we look at Henkel’s specification for the cloth we find the following statement:
“65/35 warp polyester cotton cloth”
What this means is, the warp (we’ll get to what that is in a minute) is made of a 65% polyester/35% cotton blend. This specification tells us that the cloth that came into the Henkel factory had to have a warp made of this blend, or it would be rejected. So what is warp…let’s do some duct tape terminology here.
In this wiki image we have a good illustration of how a woven cloth is constructed:
So the cloth of a piece of tape will have a larger diameter “weft” cord that is woven laterally and then a finer cord, but higher thread count per inch “warp” that is woven in and out of the rows of weft. It is the warp in the cloth construction we are concerned with because the microscopic analysis of the weft showed to be identical for all five pieces of tape (i.e. they all contained a weft made of “off-white poly (d) sl ribbon”). But the warp is the one where the gas can tape had a cotton content, where the duct tape pieces at the crime scene did not. It should be noted that in addition to the “difference” of the cloth content between the pieces at the crime scene and that on the gas can being listed on page 627 of this document the similarities of the cloth are also noted on that page. Those similarities are – the cloth weave is identical for thread count for both warp and weft:
So between backing, adhesive, weave and cloth content we are left with only one dissimilarity between the four pieces of duct tape at the crime scene compared to the one piece of duct tape on George’s gas can – the cotton content of the warp. As we’ve established in the product specifications from Henkel, the warp had to have originally been made of 65% polyester/35% cotton, so where is the cotton in the crime scene duct tape, and does it’s absence mean the tape couldn’t have come from the same roll as the gas can duct tape?
The answer to the last question is – No…it doesn’t mean they didn’t all come from the same roll. And the explanation to why we can answer that way comes in the answer to “where did the cotton go?” The first important thing to understand about cotton is that, well, it’s a plant. When you wear a 100% cotton garment you are wearing 100% plant material. Cotton thread is 100% pure cellulose from the cotton plant. Cellulose is a carbohydrate which for all you dieters out there reduces to “a long chain of sugar molecules”. You’re wearing a starch when you wear cotton. This open-cell naturally occuring polymer “starch” of cotton is what makes it more absorbent than say a synthetic fabric such as polyester. But the organic nature of cotton is also what makes it far more susceptible to decay than the synthetic fabrics. Cotton, just like the organic cells of your body, decomposes under microbial action…because it’s pure food for those microbes. This is why cotton is used in what is called “Cotton Strip Assays” which are tests of soil to measure the microbial activity in a given piece of property. The results from this test can determine if the soil is sufficient for crop growth.
A cotton strip assay consists of taking cotton strips and burying them in the soil and then coming back in a set number of days and pulling strips out of the ground and analyzing them for how much they have decayed. The scientist can then go back after another period of time has passed and pull more strips out to analyze further decay. Based on this “attack” of the cotton (i.e. how much of it has gone away), the microbial activity level in the soil can be established. You can read about cotton strip assays here and here. (The second link is interesting because it actually discusses utilizing cotton strip assays in soil analysis in the Florida everglades!) As stated in the second link, cotton is used above other media for these analyses because:
“Decomposition rates of cotton strips are exceptionally high compared to those of plant material and clearly do not represent realistic rates; pure cellulose is not the equivalent of roots or plant litter.
In other words, the cotton decomposes so rapidly that the testing period of the soil to establish the end data is significantly shortened in comparison to using other media for measurement. It simply goes away fast! In the first paper you will see that measurable decomposition is detectable within 1 week of the cotton strips being buried.
But, you might say, the cotton wasn’t buried! No, it wasn’t. It was attached to a decomposing human body, which was in a bag, which was flooded and submerged with swamp water infested with organic matter and microbial life. In fact, in contact with a decomposing body is about as microbial as you can get. So there were plenty of little microbes to find the food source the cotton content of the warp represented.
So is there really a difference between the duct tape at the crime scene and that on George’s gas can? Yes, there is, but once there wasn’t. And the difference now is one that a Henkel representative and a bug-guy can explain in very basic, easy-to-understand terms – probably with accompanying pictures!
We will address the other issues of the duct tape in later posts.
Valhall.
Related posts:
- Will Duct Tape be Casey’s Sticking Point – 95% ‘Shurity’
- Will Duct Tape be Casey’s Sticking Point? – Loose Ends
- Will Duct Tape be Casey’s Sticking Point? – The Connections
- Will Duct Tape be Casey’s Sticking Point? – A Possible Source – Update
- Will Duct Tape be Casey’s Sticking Point? – The DNA
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