Is Jerry Buting’s Claim About Sweat DNA Correct?

One of the trial attorneys for “Making a Murder” subject Steven Avery

called out former District Attorney Ken Kratz for “continuing his public misinformation campaign.” 

“He is making statements he should know are untrue, like claims about Steven Avery’s ‘sweat DNA’ being found on the hood latch of the Rav4,” says [Jerry] Buting. “There is no such thing as ‘sweat DNA.’ DNA is found in all nucleated cells, but there has never been a test to determine that a sample of DNA came specifically from perspiration.” 

He adds: “What Attorney Kratz also has not mentioned is that there are many studies that show ‘touch DNA’ can be innocently transferred from one object to another, or one person to another, without any connection to a crime. 

Is he right?

Yes. It is well established that “sweat contains no DNA.” Brief of Appellee, Ashcraft v. State of Indiana, 2012 WL 4937683 (Ind.App. 2012). That said, “people often slough off skin cells containing DNA when they sweatDNA is often present on articles of clothing, including hats.” State v. Norman, 2003 WL 22999499 (Ohip App. 2003).

As Buting noted, DNA is found in all nucleated cells:

DNA is the chemical which encodes all genetic information. DNA is located in the nucleus of all nucleated cells in the human body, remains constant throughout a person’s life, and is identical in each cell-i.e., the DNA extracted from a man’s blood cells is identical to the DNA extracted from his sperm cells. Each person’s DNA is unique, with the exception of that of identical twins….

DNA is composed of two strands made of chains of chemical bases called nucleotides. Each nucleotide is one of four chemicals which compose a four-letter organic alphabet. The strands are very long, containing billions of nucleotides which can be arranged in any order along the strand. The order of the nucleotides determines certain characteristics which will be expressed in an individual’s physical or mental traits. Each sequence of nucleotides which encodes for a specific characteristic is a gene, and can be thought of as one word using the four-letter alphabet. The two strands are joined together and twisted into a shape referred to as a double helix, which can be envisioned schematically as a twisted ladder. The order of the nucleotides on the opposing strand is complementary in that certain nucleotides always pair with one another. It is possible to separate the two strands of DNA, and they will rejoin in the original manner because of the specific ways nucleotides pair with one another. State v. Pennington, 393 S.E.2d 847 (N.C. 1990).

As a result, as Buting claimed, there is no test to determine whether DNA came from skin cells in sweat or other nucleated cells. As Dr. Ann Hunt testified in State v. Ramsey, 2010 WL 9070062 (Mich.Cir.Ct. 2010):

Q. What other fluids or aspects of the body contain all that?

A. Any nucleated cells in the body would contain DNA. So, um, in our, in our forensic work we basically work with um, white blood cells will have a, a large amount of DNA. Um, skin cells again. We work with, as a known sample we ask for a swabbing from the inside cheek area because there’s a very high level of um, nucleated cells inside the cheek. Um, semen samples. Ah, the apiifolia cells from the female, um, in a sexual assault case have a very high yield of DNA. And then the sperm cells also, um, contain DNA so we can do comparisons on those samples as well. We’ve gotten numerous samples from chewing gum, to lollipop sticks, to um, just anything that would contain what we would um, expect to find nucleated cells on.

Q. Sweat from sweat glands, is that?

A. The cells, the nucleated cells that are shed in um, sweat would contain the DNA.

Q. OK. Now ah, can DNA anywhere, I mean not just here, but anywhere in, in the nation, can DNA tell you as a lab person for instance when ah, a certain act occurred, or when a piece of clothing was worn, can it tell you that?

A. Um, there are serological tests um, for example, in sexual assault cases where we can um, have a time frame um, sperm cells will only last in an individual’s body for so long. On clothing garments, um, until an item is washed, um the DNA is relatively stable in a dried state. Um, so I wouldn’t be able to give a time frame on a dried item of clothing material.

Q. And I guess, that was a good answer to a bad question. In other words, what I’m looking or what I’m asking you is that, ah, you can tell from DNA analysis if somebody wore a particular piece of clothing. But can you tell when they wore it?

A. Um, we can include or exclude an individual as being a potential donor to DNA found on a clothing item. However, a, a time frame would not be possible.

The first part of this testimony establishes that you can’t tell whether DNA can from skin cells in sweat as opposed to any other nucleated cells. Here’s further testimony on the subject by Dr. Christopher Chillseyzn in State v. Gaudette, 2005 WL 6958954 (N.J.Super.L. 2005), indicating that it’s impossible to distinguish DNA in sweat/skin from other DNA.

Q. And DNA from epithelial skin as opposed to say DNA from sweat, is it different or is it going to come out all the same if it’s the same person? Jessica’s epithelial DNA —

A. All cells in the body contain, well, except for sex cells, all cells will contain the same DNA from any tissue type from any person.

Q. So looking for Jessica’s DNA on Jessica’s shirt, would that tell you whether that came from saliva or sweat, could you differentiate?

A. No. Well, sweat itself wouldn’t contain the DNA. Epithelial cells that the sweat washes off that has the DNA. But no, I wouldn’t be able to tell. (emphases added).

The second part of Dr. Hunt’s testimony establishes that you can’t determine when the DNA was left behind, which is a question that a few readers have asked me.

Finally, what about Buting’s reference to touch DNA? I will cover that when I write my post on the final episode of the Unsolved Podcast.

-CM