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NARRATOR: Early one morning
in a deserted area outside of Phoenix, a
motorcyclist discovered
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the body of a young woman. She had been beaten, bound,
strangled, and possibly raped.
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The surrounding plants would
tell more about her killer than any other single
piece of evidence.
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[theme music] When investigators from
the sheriff's department arrived at the crime scene, they
gathered every possible piece
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of evidence. The victim was nude except
for a pulled-up tank top and a t-shirt wrapped
around her neck, which was
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probably used to strangle her. Her wrists and ankles were
loosely bound with shoe laces
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and what looked like
picture hanging wire. Nearby, investigators
found a syringe,
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some articles of clothing. Then they heard some evidence. [beeping] It was a pager found deep in the
grass a few feet from the body.
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The discovery of the pager
triggered a larger search, and the photographer took
some aerial photographs.
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There appeared to be a
circular area of matted grass where an altercation
possibly took place.
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[dramatic music] Police took the victim's
remains to the medical examiner for identification and autopsy.
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A fingerprint search
identified the victim as 30-year-old Denise
Johnson, a single mother
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of two young children. She was born and raised
in an area of Phoenix known as, "the Projects."
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HESTER JOHNSON: She
wasn't a bad girl. She-- with some of
her friends, I think she got with the wrong friends.
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Ain't gonna say they made
her do these things now. She hung around with people
that liked to party, drink,
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and I don't really know
what they were doing. But she, you know, she
was out there in the world
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with people that
did drugs, I'm sure. And sometimes, I think
she trusted too much.
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NARRATOR: Denise made her living
on the streets of Phoenix. She had a history of
short-changing truck drivers
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in various drug deals at local
truck stops, which earned her the nickname, "Twist Momma."
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CHARLES NORTON: Her
friends cautioned her that her lifestyle
was probably going to find her in a lot of trouble
someday, and eventually it did.
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NARRATOR: But who ended
Denise Johnson's life? The investigation
began with the pager
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found lying near the body. It belonged to this man, a
local trucker named Mark Bogan.
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He said that, on his way home
from work the night before, he stopped to make a phone call.
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That's when he met Denise
Johnson for the first time. Hi! How you doing? Hello, there.
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NARRATOR: Bogan said she asked
for a ride to the interstate. Sure, why not? Thanks!
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[engine starting] NARRATOR: Once inside the truck,
she made some sexual advances.
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They pulled off the road
and had consensual sex in the cab of his truck. [dramatic music]
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Afterwards as he was
dropping her off, he said she attempted to
steal some of his things
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off the dashboard. Oh, I had a really good time. Unh, so did I, baby. Did you? Oh, always when I'm in the
company of a lovely lady.
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I would really love to
have my wallet back. NARRATOR: After a brief scuffle,
he retrieved his wallet.
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She got out and left on foot. Go to hell! NARRATOR: Bogan said that
was the last he saw of her.
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[engine starting] The next morning, he noticed
his pager was missing, assumed he had lost it, and
called the pager
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company to report it missing. During the interrogation
of Mark Bogan, investigators noticed scratch
marks on the side of his face.
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If there were scratches
on the suspect's face, then you would expect that if
those were in fact inflicted
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by fingers or fingernails
of the victim, there should be some residue
of either the skin cells
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and or maybe even blood
under the fingernails. NARRATOR: The autopsy
of Denise Johnson
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revealed no skin or blood
under any of her fingernails. The medical examiner
found that Denise
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Johnson's death was
caused by asphyxiation due to strangulation. Blood tests showed
cocaine in her system.
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However, there were no signs
of any type of sexual activity. There was no semen found, no
foreign hair, clothing fibers,
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or saliva found
anywhere on her body. The autopsy told
investigators how Denise Johnson
died, but provided
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no clues about her killer. Their one suspect, Mark Bogan,
was apparently a dead end.
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The sheriff's office had not
only a murder, but a mystery. On the day after police
discovered Denise Johnson's
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body, homicide
detective Charlie Norton was assigned to the case. CHARLES NORTON: I decided
that it would help me,
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as the investigator, to
go out and familiarize myself with the scene
where the body was found.
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NARRATOR: Denise Johnson's body
was discovered in a remote part of Maricopa County,
about a half an hour
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away from downtown Phoenix. Charlie Norton was
looking for anything out of place or unusual.
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Anything that might have been
overlooked the day before. Then he saw it. Something peculiar on
a Palo Verdes tree,
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just a few feet from
where the body was found. CHARLES NORTON: I had parked
my car on the pavement.
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I noticed that there was a-- a branch that was hanging over. And when I looked
at that branch,
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I noticed that there
was a fresh abrasion, and I had no idea
what it might mean.
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But I took a picture of it. Then I took some beans off
of that particular tree. NARRATOR: Meanwhile,
investigators
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confiscated Mark
Bogan's truck to look for possible
evidence linking him or his truck to the crime scene.
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It was completely clean. No fingerprints,
semen, blood, saliva, hair, or clothing fibers.
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No evidence at all that Denise
Johnson was even in the trunk. But when investigators
and police photographers
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looked in the back
of the truck, they made an interesting discovery. They found two bean pods
from the Palo Verdes tree.
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Was it possible that Bogan's
truck brushed against the Palo Verdes tree at the crime scene
causing two bean pods to drop
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into the back of the truck? The problem was
Palo Verdes trees are very common in Arizona.
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There are tens of thousands of
them in the Phoenix area alone. But Charlie Norton's
boss had an idea
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to see if DNA testing
could match the bean pods from Bogan's truck to
the tree with the abrasion
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at the crime scene. I suggested to
Charlie the time-- I said, you know-- I said, it'd be a real good
idea if we could find someone
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somewhere in the United
States that is involved in DNA testing the plant life. You know, I asked, what the
hell have we got to lose?
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You know, where are
we gonna go from here? What's the number for ID? NARRATOR: Norton started working
the phones calling scientists
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all over the United States. CHARLES NORTON: Yeah,
I got answers like, it couldn't be done, to
maybe it could be done,
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and that if it could be
done that the cost would be prohibitive. NARRATOR: 15
telephone calls later,
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he found someone who offered
some hope, ironically, just 100 miles away
at the University
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of Arizona in Tucson. I saw that as sort of a public
service thing that we could do.
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That we'd show some of this
science is relevant to people and maybe is a way that's
not quite as obvious,
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sometimes, through agriculture. NARRATOR: Could DNA really
show that one plant or tree
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was different from
another even though they were the same species? DNA is present in all
cells of all living things.
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It's a little like
a computer program containing all of the
information necessary to create
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a living thing. All humans have
different DNA profiles except for identical twins.
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In the early 1980s, Dr. Alec
Jeffreys, a British scientist, discovered a test that made
it possible to identify
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an individual's DNA profile. Jeffreys' breakthrough
technique was first used in a criminal case in 1986.
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But plant DNA had never been
used in a criminal case, and scientists
weren't even sure they
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could figure out a
way to extract DNA from the Palo Verdes seed pods. Well, we certainly
use fingerprinting a lot
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in agriculture, but
we've never looked at this particular
species, this tree. Nobody has probably ever done
any much biology on it at all.
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NARRATOR: Prosecutors had
circumstantial evidence linking Mark Bogan to Denise
Johnson's murder,
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but they needed something
more definitive. They knew they would have
to prove that Bogan was
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at the crime scene,
and the Palo Verdes pods were their best chance. The scientists had no
idea that their research
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would be the cornerstone
of a murder case. The Arizona Sheriff's
Department wanted
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to know if there was any way
scientists could match the two seed pods found in the back of
Mark Bogan's truck to the Palo
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Verdes tree next to
where they discovered Denise Johnson's body. But there were thousands of
Palo Verdes trees in the Phoenix
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area alone, and there
had never been a DNA test on this type of tree. We had to learn how to do the
analysis so that we could say,
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do trees look different from
each other in the species? Because what we
wanted to know was not
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was this a Palo Verde
tree, but could I match it to that specific tree. NARRATOR: Dr.
Helentjaris used what
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is known as a Randomly Amplified
Polymorphic DNA technique or RAPD. This is a less common
test than RFLP, the one
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used in searches for human DNA. PAUL KEIM: One of the great
things about RAPDs is,
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is that you're able
to know nothing about an individual species
or type of organism.
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You don't have to have any
prior knowledge about it. All you have to do is get
DNA and the method works.
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NARRATOR: The test
begins by removing the beans from their
hard outer shell or pod.
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TIM HELENTJARIS: Seeds have
DNA both from the mother tree and other trees that
would have pollinated it.
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So we need to get rid
of those and just use the pod material,
which will only have DNA from the mother tree.
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NARRATOR: The shells are
put into liquid nitrogen making them brittle and easier
to grind into a fine powder.
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A chemical solution
is added and the DNA floats free, a sticky
bundle of complex molecules.
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The sample amount of
DNA from a seed pod is too small for analysis. So scientists
increase the sample
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size by copying the DNA strand. They use a technique
called Polymerase Chain Reaction or PCR.
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The copying process takes
place in a DNA thermal cycler. Within a few hours, this
technique multiplies
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the DNA millions of times. The DNA is then placed
into various lanes of a gel with a dye added
and then subjected
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to an electrical field. Under ultraviolet light,
it's possible to see how the electrical current draws
the negatively-charged fragments
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through the gel to the
positive end at the top. The results resemble a bar-code,
the genetic fingerprint
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of a Palo Verdes tree. These fingerprints
enabled Helentjaris to make an important discovery.
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The two pods found in
Mark Bogan's truck matched each other, and
they also matched
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the pods taken from the
tree at the crime scene. The tree next to where Denise
Johnson's body was discovered.
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Every other Palo Verdes
tree tested had a completely different DNA profile. It was the result that
investigators and the district
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attorney had hoped for. It wasn't the criminal itself,
but it was a particular tree
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that we had to identify. And in fact, they had matched. We had matched that up. He was able to take
the original samples,
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take a part of the samples
from the pickup truck, determine that those two pods
came from the very same tree.
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Then he compared those with all
the samples from all 12 trees and matched it to a tree
there at the crime scene.
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Not knowing that the
tree had the scrape on it to which he matched it. NARRATOR: But there were only
12 trees in the initial test,
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and the prosecution felt that
wasn't a large enough sample. They needed to show a
potential judge and jury
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that all of the Palo
Verde trees in Arizona had a different DNA profile. So the district attorney
sent Helentjaris pods
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from 100 different
trees asking him to prove that each had a
separate and distinct DNA
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profile. And he tried to
trick Helentjaris. I did not tell Dr.
Helentjaris that I had gone back
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out to the scene,
had a deputy take a sample from the same tree
which had the scrape on it.
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NARRATOR: Dr. Helentjaris
proved that each of the pods had a different DNA profile,
and he also discovered
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the prosecution's trick. I called him. And I was a little
concerned, because-- you know, while we could tell
all these trees apart and so
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forth-- but we put
the sample back in and it looked like
it matched one of these supposedly random trees
that they'd gone out and done.
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It's almost like a
touchdown in the end zone. I knew it. I knew he had hit on it.
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Out of 20 other samples that
he had tested on one gel, he hit and matched perfectly.
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NARRATOR: Police
arrested Mark Bogan and charged him for the
murder of Denise Johnson.
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He entered a plea of not guilty. But the question remained. Would this new DNA evidence
be admissible in court?
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No one had ever introduced
plant DNA as evidence in a criminal trial anywhere. SUSAN BOLTON: We held
a preliminary hearing
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before the judge only to
review the scientific evidence to see whether or not it was
evidence that was generally
00:15:50
accepted in the
scientific community as both valid and reliable. NARRATOR: For three days
without a jury on hand,
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lawyers and scientists
argued whether plant DNA should be admitted
into a criminal trial
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for the first time ever. SUSAN BOLTON: What all of
the scientists agreed about was that plant DNA like human
DNA was unique to each plant
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and, if properly tested, could
distinguish one Palo Verdes tree from another
Palo Verdes tree,
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and there seemed to be
no dispute about that. Judge Bolton denied
the defense motion
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to prohibit Dr.
Helentjaris's testimony, thereby allowing
the DNA evidence to be admitted at the trial.
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In setting a precedent, Judge
Bolton had made DNA history. We were the
first criminal case
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in the country that used a DNA
comparison of plant material to-- as a piece of evidence.
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NARRATOR: Now armed with
the potent weapon of a DNA fingerprint, the
prosecution went
00:16:58
to trial attempting
to prove to a jury that Mark Bogan
murdered Denise Johnson. What happened to Denise Johnson
on the night of May 2, 1992?
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The prosecution believed
that Mark Bogan met Denise Johnson at a phone booth. Hi!
00:17:20
How you doing? NARRATOR: They spoke briefly,
and Denise asked for a ride. Sure, why not?
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Thanks! [engine starting] NARRATOR: They drove
to a deserted location for what was going to be a
consensual sexual encounter.
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How would you like
to have some real fun? NARRATOR: Bogan asked
Denise if she would agree
00:17:55
to some light bondage,
and tied her wrists and ankles with some
picture-frame wire
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and shoelaces. Some of Bogan's ex-girlfriends
would testify that he enjoyed bondage, and another
witness told investigators
00:18:11
that she saw the same type of
wire in the cab of his truck just a few days earlier.
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No! No, stop it! No! NARRATOR: At some
point, Denise Johnson objected to what was happening
and asked Bogan to stop.
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Leave me alone! NARRATOR: Johnson
got out of the truck and tried to run with
Bogan fast behind.
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Quickly, the situation
turned violent. The two struggled
in the open field. Bogan lost the pager he
carried on his waist,
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which fell into the high grass. Bogan strangled Johnson
with her own T-shirt. Then he dragged her body under
some nearby bushes and left.
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As Bogan drove away, his truck
brushed against a Palo Verdes tree leaving the abrasion.
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Two seed pods dropped into
the back of his truck. An eyewitness saw a white truck
similar to the one Bogan owned
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coming out of the road
leading from the crime scene, going through a stop
sign, and speeding off
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in the direction of Phoenix. The witness said it was
about 1:30 in the morning. Bogan lived 18
minutes from the area.
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And his wife told police she
awoke as Mark returned home just after 2:00 in the morning.
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Most of the evidence
against Mark Bogan was circumstantial, the lost
beeper, the picture-frame wire,
00:19:36
his interest in
bondage, and the witness who saw a white truck in
the vicinity of the crime
00:19:42
scene the night of the murder. But the most critical evidence
in the case was the plant DNA.
00:19:50
SUSAN BOLTON: There
wasn't a fingerprint, there wasn't a drop of
blood, there wasn't a hair.
00:19:55
There were none of those
things that anybody could say were part of
the victim's body found--
00:20:01
must have been left by the
victim on the defendant or on the defendant's
property or vise versa.
00:20:08
He had admitted
to the detectives that he'd washed his
truck the next morning. He got rid of all of the
evidence in the truck
00:20:14
except for two Palo Verdes pods. They needed evidence that
placed Mark at the scene,
00:20:21
because he did have
a credible story. As a prosecutor, I
had a mantle of evidence
00:20:25
that I wanted to place upon
the shoulders of the defendant. The Palo Verdes pods took
the mantle by the drawstring
00:20:34
and wrapped it around his neck. NARRATOR: Unable to challenge
Dr. Helentjaris's findings
00:20:40
themselves, the
defense challenged the evidence implying
the pods were planted in the back of Mark's truck.
00:20:47
But investigators said
the seed pods were found in Bogan's truck
before samples were
00:20:53
taken from the crime scene. If I was going
to plant evidence, I would plant something that--
00:20:58
that I know that I
could match later on and probably be a little bit
more assured of a conviction.
00:21:10
NARRATOR: The jury found
Mark Bogan guilty of murder in the first degree. He was sentenced
to life in prison
00:21:17
without parole for
at least 25 years. The appellate court
upheld the verdict. Mark Bogan continues to
maintain his innocence,
00:21:28
and the appeal
process is continuing. I'm trying to
forget this case, because I'm the only person on
the planet that lost to plant.
00:21:36
It was something that hadn't
been done before, something that was certainly very
different from the routine
00:21:45
things that we do
every day as judges. But I love my
daughter very much. I love all of my children.
00:21:53
But it's something we
just have to go through. It's done. I don't know what
in the world that
00:22:01
could have tripped him off to-- to hurt her like that. I don't know, but I hope
one day we'll find out.
00:22:09
[music playing]