Unfinished forensics in Trayvon Martin case

August 2, 2013

Friday, August 2, 2013

Good morning to all of our friends:

I write this morning regarding unfinished forensics with Trayvon’s case and to urge Benjamin Crump to consult with someone who is knowledgeable about forensics before he decides whether to sue George Zimmerman for wrongful death.

Piranha Mom’s comment at 12:09 am inspired me to write this post.

If a civil claim is filed against Zimmerman by Trayvon’s family, Professor Fred and all of us must put together the DEFINITIVE narrative, citing each movement with justification and evidence, and supply it to Trayvon’s family and attorneys.

We know what happened.

We have had the forensic evidence at our fingertips — and we know it all by heart. We were open in our analysis.

We DIDN’T expect we had to provide this to the prosecution.

But they were so full of hubris and the big award Bernie was to receive, and paid little attention to evidence. Bernie even thinks Trayvon took part in the battle, not that he was struggling to get away. If the prosecutor has no faith in the victim, or in the chief witness for the prosecution, what could we expect to get?

The verdict we got.

Won’t make THAT mistake again!

Yes, Piranha Mom is right and here are three glaring examples.

Amy Siewart, the crime lab firearms analyst who examined Trayvon’s sweatshirts, apparently never read the autopsy report or conferred with Dr. Bao regarding whether the bullet holes in the sweatshirts aligned with the entry wound in Trayvon’s chest. Evidently, no one at FDLE or any member of the prosecution team thought about that possibility either.

Yet, that was the first thought that occurred to me when I read that first document dump and LLMPapa was all over that issue too. I wrote about it and he made several videos about it. Both of us discussed the implications.

We even argued with the self-described crime scene expert from Jacksonville, Michael Knox, about the proper conclusions to draw from that evidence.

Massive and inexcusable failure of LE and the prosecutor’s office not to see and comprehend the significance of that evidence.

Massive and inexcusable failure by BDLR not to use the State’s DNA expert, Anthony Gorgone, to clear-up the confusion created by the defense regarding whether rain can wash away DNA and whether packaging Trayvon’s sweatshirt in a plastic biohazard bag would degrade all DNA present, such that it could not be detected with STR/PCR.

Siewart also should have been questioned regarding (1) the unusually strong kickback of a KelTec 9 semiautomatic handgun when fired with one hand, and (2) whether the distance between the two spires on the rear gunsight match the distance between the two pinholes on the tip of Zimmerman’s nose that bled so copiously.

I believe those distances match and Siewart could testify that the gun could have caused the injuries to Zimmerman’s nose, if he fired the fatal shot within a few feet of his face while holding the gun with one hand as Zimmerman described.

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What Does Zimmerman’s Blood Tell Us?

September 23, 2012

We need to focus today on the information available to us regarding the fatal shot in order to determine as best we can the respective positions of Zimmerman and Martin when Zimmerman fired the fatal shot.

As we do so, we have to keep in mind that there are two bloodstains on Martin’s shirt, which he was wearing under the hooded sweatshirt. DNA analyst Anthony Gorgogne has identified Zimmerman as the source of Stain A. He also concluded that Stain D is a mixed sample of Zimmerman and Martin.

In yesterday’s article on the DNA results, I mentioned that those are the only bloodstains on Martin’s clothing that contain Zimmerman’s DNA. Depending on their location, I concluded that the bloodstains may be the result of dripped blood from Zimmerman’s head as he leaned forward over Martin’s body while he was dead or alive, or transferred blood from his hands as he touched Martin’s shirt.

Note that if we assume the fingers and palms of Zimmerman’s hands were bloody with his own blood, we would expect to see his blood on Martin’s hooded sweatshirt, if he grabbed Martin’s two sweatshirts together with his left hand and pulled them down and slightly to his left as he fired the fatal shot.

Gorgogne did not find Zimmerman’s blood or DNA on the hooded sweatshirt. That probably means he did not have any blood on the underside of his left hand and fingers when he gripped the shirt and sweatshirt or, if he did, he did not transfer it to the sweatshirt.

It also may mean that he did not grip the sweatshirts, although I still believe he did.

Recall that Gorgogne did not detect any of Zimmerman’s blood on Martin’s sweatshirt. Witnesses Mary Cutcher and her friend Selma saw him straddling Martin’s back and leaning forward touching his back and neck with his hands after the shot. Therefore, I do not believe he had any blood on his hands.

No blood is visible on his hands in the photographs taken by police at the station house after the shooting.

That does not mean that blood was not on his hands earlier, however, because the police incredibly permitted Zimmerman to wash up in the washroom at the station house before the photographs were taken. That is inexcusable. It is what it is, however, and we cannot change it.

We do know that Gorgogne identified Zimmerman’s blood on the grip of his Kel Tec 9 semiautomatic handgun. Could that bloodstain have been already present before the incident that resulted in Martin’s death?

For example, DNA preserves indefinitely in a dried bloodstain, so Zimmerman might have deposited his blood via transfer to the grip sometime before the incident with Martin on February 26th. He might not have known it was there. I do not recall seeing any blood on the grip of his gun in the photographs that were recently released. Given PCR’s exquisite sensitivity, not much blood would have to have been present to yield a complete DNA profile.

Now let us take a look at Amy Siewert’s lab report. She is a firearms expert and her report was in the first document dump. She described the locations of the two holes in the sweatshirts and I compared what she wrote to Dr. Bao’s description in the autopsy report regarding the location of the entry wound.

Siewert said the holes in the sweatshirts aligned with each other and were 7 inches below the shoulder/neck seam.

Dr. Bao said the entry wound was 1 inch to the left of the midline and 1/2 inch below the nipple.

I am 1-inch taller and the same weight as Trayvon. I placed a mark on my chest corresponding to the location of the entry wound and then I took one of my white tee-shirts and placed a mark 7 inches below the shoulder/neck seam. I put on the tee-shirt and, using the marl on my chest, I marked the location of the entry wound on the tee-shirt.

I took off the tee-shirt and measured the distance between the two marks.

The two marks are a little over 3 and 1/2 inches apart. The mark representing the hole in the sweatshirts is above and slightly displaced toward the left shoulder.

To perform this comparison with precision, one would need to place the sweatshirts on Trayvon’s body and precisely measure the distance between the holes and the entry wound and determine the angle of their displacement from the vertical.

I could not do that, so I approximated the distance at 3 inches with a displacement toward the left shoulder.

Could my conclusion have been mistaken? I do not think so, but I have to admit that it is certainly possible. Fabrics stretch and there was only so much that I could do to reproduce the state of the State’s evidence.

I hope someone on the prosecution team followed up with Siewert and Dr. Bao to nail down this point as well as the apparent discrepancy between her characterization of the hole as having been caused by the muzzle of the gun in contact with the fabric and his characterization of the shot having been fired from an intermediate range (i.e., 0.5 centimeters to 1 meter).

I note for the record that Dr. Bao described the entry wound as 3/8 inch in diameter with a 2 X 2 area of stippling around the wound.

Stippling is caused by unburned gun powder that enbeds in the wound and its periphery. The farther away the muzzle of the gun, the larger the area of stippling. With handguns there is no stippling apparent when the muzzle of the gun exceeds 1 meter from the entry wound at the time the shot is fired..

Contact wounds characteristically cause the skin to tear. This condition is called starring and it’s caused by the expanding gasses released by the burning gunpowder.

Siewert observed torn fabric that spread out from the holes caused by the shot. She prepared some cutouts using fabric from the two sweatshirts (actually the interior one has been redesignated as a shirt by the DNA analyst) and test fired Zimmerman’s gun using the same ammo from several different distances, including a contact shot. The tearing in the result from the experimental contact shot matched the tearing in the hole in the sweatshirt and that is why she concluded that it was a contact shot.

Dr. Bao did not note any tearing or starring around the entry wound.

D. Vincent di Maio, a respected forensic pathologist and the former Medical Examiner for Bexar County, Texas (San Antonio) reviewed Dr. Bao’s autopsy Report and estimated the muzzle of the gun was 2 to 4 inches from the entry wound when Zimmerman fired the fatal shot.

Dr. Bao characterized the fatal shot as “Directly, front to back.”

That is all the evidence we have.

Consider these questions:

(1) Did Zimmerman grip Martin’s sweatshirt and shirt with his left hand?

(2) If he did not (or even if he did) how did he immobilize Martin so that he could aim and squeeze off the perfect shot to the heart, or was it just a lucky shot?

(3) How and when did Zimmerman sustain the injuries to his nose and the back of his head?

(4) Do you believe the injury to his nose was caused by the recoil of his gun when he fired the fatal shot?

(5) What do you believe explains the presence of Zimmerman’s blood on Martin’s shirt?

(6) What do you believe explains the presence of Zimmerman’s blood on the grip of his gun?

As I said, I hope the prosecution has figured out the significance of the evidence as it is important to the outcome of the case.

I still believe that the agonizing shriek that abruptly ended with the shot and the interrogation and begging that preceded it establish beyond a reasonable doubt that Zimmerman was not in imminent danger of being killed or suffering serious bodily injury when he shot and killed an unarmed Martin “evincing a depraved indifference to human life.”


DNA Testing and the Results from Zimmerman’s Gun

September 19, 2012

I. Introduction

I was going to publish an article on a Motion for a Change of Venue today, but decided to postpone it and do an article on DNA instead.

II. Forensic DNA Testing

All crime labs use the same PCR test that the Florida lab used. The test was developed by the FBI Crime Laboratory. It uses the PCR process developed by Dr. Kary Mullis, a biochemist who won the 1993 Nobel Prize in Chemistry for inventing it. He is a true genius and wild man and his story is worth checking out.

Basically, PCR imitates the cell division/ replication process to create millions of copies of targeted sequences of DNA.

The FBI selected 13 polymorphic (i.e., variable) human genes that are independent of each other.

Let’s say, for example, that each of the thirteen genes might have 10 known variations or genotypes in the human population.

Databases, each consisting of Caucasians, Blacks, Hispanics, Native Americans, and Asians, have been genetically studied to identify the frequency of each known genotype within each group.

Let’s say the distribution of the 10 genotypes with the first gene, which I will call Nikko, because that is my parrot’s name, is as follows:

Gene = Nikko

Database: Human Population

Genotype A: 1%
Genotype B: 5%
Genotype C: 10%
Genotype D: 15%
Genotype E: 19%
Genotype F: 23%
Genotype G: 17%
Genotype H: 6%
Genotype I: 3%
Genotype J: 1%

Total: 100%

The distribution of the 10 Nikko genotypes in each of the racial groups will differ somewhat from their distribution in the human population and from their distribution in each of the other racial groups.

This part is key, so pay attention. The 10 genotypes of each of the 13 genes are known to occur independently of each other. For example, your Nikko genotype (let’s say Type H) does not make it any more or less likely that you will have a particular genotype at any of the other 12 genes.

To illustrate this point, let’s consider the genes responsible for eye and hair color. We know they are not independent because those genetic traits are obviously linked. Blonde hair and blue eyes are an example and you can probably think of others.

Forensic DNA testing selects genes that are known to be inherited independently from each other.

Why is that important?

Because you can use the Product Rule to calculate the odds that a person will have a particular set of genotypes or genetic profile for the 13 genes.

For example, as before let’s say your Nikko genotype is Type H, which you share with 6% of the human population.

Let’s call the next genetic site Brutus. Let’s say your Brutus genotype is Type D, which you share with 17% of the human population.

What percentage of the population would be expected match your genetic identity at Nikko and Brutus?

The answer is 0.0102 (0.17 X 0.06 = 0.0102) or about 1% of the human population.

To calculate the distribution or frequenct of your genotype in your racial category, you would use the Product Rule to multiply the percentages for the distribution or frequency of your genotype for the Nikko and Brutus genes in your racial category or database.

You might find, for example, that the frequency of those two genotypes occurring together might vary by up to as much as 10% from one racial category to another, but usually they do not vary by that much.

III. DNA Test Results in the Zimmerman Case

A. The grip on Zimmerman’s gun

Let’s take the swab collected from the grip.

First, the analyst tested for the presence of blood by swabbing a discrete portion of the grip and the test reacted positively, indicating the presence of blood.

Note that no blood was detected on the other locations (trigger, slide and holster).

BTW, red blood cells do not have a nucleus. White blood cells do and DNA tests are designed to extract and purify the DNA in the nucleus of white blood cells.

The absence of blood does not mean that no DNA will be present as that can happen if saliva or living skin cells are present. The cells in saliva and skin cells have a nucleus.

The analyst ran the PCR test on the blood that was present on the grip and obtained a complete DNA profile of the major contributor (i.e., a result identifying all 13 genotypes of the questioned sample, plus the sexual identifier).

This profile matched the known profile of George Zimmerman that was obtained from a buccal swab.

Using the Product Rule that I explained, the frequency of this profile is:

1 in 11 quadrillion Caucasians:
1 in 1.5 quintillion African Americans; and
! in 57 quadrillion Southeast Hispanics

Obviously, those numbers exceed the known population of the world. They were generated by multiplying the 13 genotype frequencies of his complete profile in each of the three listed databases.

The bottom line is George Zimmerman is the major contributor of the blood on the grip of his semiautomatic.

The analyst further determined that there was at least one other human contributor to the DNA sample obtained from the grip, but excluded Trayvon Martin as a possible source of that DNA.

How is that possible?

B. Alleles and Genotypes

All genotypes are composed of two alleles. One allele is inherited from the father and the other is inherited from the mother.

Let’s assume that the mother’s alleles are 1 and 2 while the father’s alleles are 3 and 4. What are the possible allele combinations their children might have?

1, 3
1, 4
2, 3
2, 4

What if they shared an allele? For example, the mother is 1, 2 and the father is 2, 3? You still have four possibilities. The possibilities are:

1, 2
2, 2
1, 3
2, 3

Why are alleles important to forensic DNA testing?

The answer is they are useful in determining if a person can be excluded from a mixed sample.

C. Exclusion of Martin as a minor contributor of sample obtained from the grip

If the minor sample contained alleles that are not present in Martin’s known DNA sample obtained at autopsy, and his DNA sample contains alleles that are not present in the sample from the grip, he can be conclusively excluded as a contributor to the mixed sample.

D. Swab collected from the trigger

These results were not interpretable “due to the limited nature of the results.” This means not enough DNA was present to get an interpretable result.

E. Swab collected from the slide

Due to the limited DNA results obtained, this data is insufficient for conclusion purposes.

Results are consistent with the presence of at least one male individual. No determination can be made regarding the possible contribution of Zimmerman or Martin because not enough DNA is present.

This means they found some alleles common to both of them, but not enough to draw any conclusions.

F. Swab from the holster

The analyst found a mixed profile of at least three individuals. The major profile matches Zimmerman.

No profile for the minor contributor could be developed.

No determination could be made regarding whether Martin could have contributed to the mixed sample.

This means a few alleles matching alleles in his sample were present but not enough to draw any conclusions.

In other words those matches were not uncommon and could have been due to chance.

IV. Conclusion

Martin’s blood is not on the gun and his DNA cannot be confirmed as present on any of the four areas tested.


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