NARRATOR: Early one morningin a deserted area outside
of Phoenix, a motorcyclist discovered
the body of a young woman.
She had been beaten, bound,strangled, and possibly r*ped.
The surrounding plants wouldtell more about her k*ller
than any other single piece of the evidence.
When investigators from the Sheriff's department
arrived at the crime scene, they gathered
every possible piece of evidence.
The victim was nude, exceptfor a pulled up t*nk top
and a t-shirt wrapped around her neck, which
was probably used to strangle her.
Her wrists and ankles wereloosely bound with shoelaces
and what looked like picture hanging wire.
Nearby, investigators founda syringe, some articles
of clothing, then they heard some evidence.
[beeping]
NARRATOR: It was a pager, found deep in the grass
a few feet from the body.
The discovery of the pagertriggered a larger search,
and a photographer took some aerial photographs.
There appeared to be acircular area of matted grass
where an altercation possibly took place.
[screams]
NARRATOR: Police took the victim's remains
to the medical examiner foridentification and autopsy.
A fingerprint search identified the victim
as -year-old Denise Johnson, a single mother
of two young children.
She was born and raised in an area
of Phoenix known as the projects.
-She wasn't a bad girl.
She-- some of her friends, I think
she got with the wrong friends.
I ain't gonna say they madeher do these things, now.
-She hung around with peoplethat liked to party, drink,
and-- I don't really knowwhat they were doing,
but she-- you know, shewas out there in the world
with people that did dr*gs, I'msure, and sometimes, I think,
she trusted too much.
NARRATOR: Denise made her livingon the streets of Phoenix.
She had a history of short changing truck drivers
in various drug deals at local truck stops, which
earned her the nickname Twist Mama.
-Her friends cautioned herthat her lifestyle was probably
going to find her in a lot of trouble someday,
and eventually it did.
NARRATOR: But who ended Denise Johnson's life?
The investigation began with the pager
found lying near the body.
It belong to this man, a localtrucker named Mark Bogan He
said that on his way homefrom work the night before, he
stopped to make a phone call.
That's when he met DeniseJohnson for the first time.
-Hi, how you doing? -Hello there.
NARRATOR: Bogan said she askedfor a ride to the interstate.
-Why not? -Thanks.
NARRATOR: Once inside the truck,she made some sexual advances.
They pulled off the road and had consensual sex
in the cab of his truck.
Afterwards, as he was dropping her off,
he said she attempted to steal some of his things
off the dashboard.
-Well I had a really good time.
-So did I, baby. -Did you?
-Oh, always when I'm in thecompany of a lovely lady.
I would really love to have my wallet back.
After a brief scuffle, he retrieved his wallet.
She got out and left on foot.
Bogan said that was the last he saw of her.
The next morning, he noticedhis pager was missing,
assumed he lost it, and called the pager
company to report it missing.
During the interrogation of Mark Bogan,
investigators noticed scratchmarks on the side of his face.
-If there were scratches on the suspect's face,
then you would expect that ifthose were, in fact, inflicted
by fingers or fingernailsof the victim,
there should be some residueof either the skin cells
and or maybe even blood under the fingernails.
NARRATOR: The autopsy of Denise Johnson
revealed no skin or bloodunder any of her fingernails.
The medical examiner foundthat Denise Johnson's death
was caused by asphyxiationdue to strangulation.
Blood tests showed cocaine in her system.
However, there were no signsof any type of sexual activity.
There was no semen found, noforeign hair, clothing fibers,
or saliva found anywhere on her body.
The autopsy told investigatorshow Denise Johnson died,
but provided no clues about her k*ller.
Their one suspect, Mark Bogan,was apparently a dead end.
The Sheriff's office had notonly a m*rder, but a mystery.
On the day after policediscovered Denise Johnson's
body, homicide detective Charlie Norton
was assigned to the case.
-I decided that it wouldhelp me as the investigator
to go out and familiarize myself with the scene
where the body was found.
NARRATOR: Denise Johnson's bodywas discovered in a remote part
of Maricopa County, about a half an hour
away from downtown Phoenix.
Charlie Norton was lookingfor anything out of place
or unusual, anything that might have
been overlooked the day before.
Then he saw it-- somethingpeculiar on a palo verde tree
just a few feet fromwhere the body was found.
-I had parked my car on the pavement.
I noticed that there was a-- abranch that was hanging over,
and when I looked at that branch,
I noticed that there was a fresh abrasion,
and I had no idea what it might mean,
but I took a picture of it, then I
took some beans off of that particular tree.
NARRATOR: Meanwhile, investigators
confiscated Mark Bogan's truckto look for possible evidence
linking him or his truck to the crime scene.
It was completely clean-- nofingerprints, semen, blood,
saliva, hair, or clothingfibers-- no evidence
at all that Denise Johnsonwas even in the truck.
But when investigators and police photographers
looked in the back of the truck, they
made an interesting discovery-- they found
two bean pods from a palo verde tree.
Was it possible that Bogan'struck brushed against the palo
verde tree at the crimescene, causing two bean pods
to drop into the back of the truck?
The problem was, palo verde trees
are very common in Arizona--there are tens of thousands
of them in the Phoenix area alone.
But Charlie Norton's boss had an idea--
to see if DNA testing could match the bean
pods from Bogan's truck to the tree
with the abrasion at the crime scene.
-I suggested to charlie atthe time, I said you know,
I said it would be a real goodidea if we could find someone
somewheres in the United States that
is involved in DNA testing of plant life.
And I said what the hell have we got to lose?
You know, where are we gonna go from here?
-What's the number for ID?
NARRATOR: Norton started working the phones,
calling scientists all over the United States.
-I got answers like itcouldn't be done to maybe
it could be done, and that if it could be done
that the cost would be prohibitive.
NARRATOR: Fifteen telephone calls later,
he found someone who offeredsome hope-- ironically, just
miles away, at the University
of Arizona in Tucson.
-I saw that as sort of a publicservice thing that we could do
that would show some of this science
is relevant to people in maybesuch a way that's not quite as
obvious sometimes through agriculture.
NARRATOR: Could DNA reallyshow that one plant or tree was
different from another, even though they
were the same species?
DNA is present in allcells of all living things.
It's a little like acomputer program containing
all of the information necessaryto create a living thing.
All humans have different DNA profiles,
except for identical twins.
In the early s, doctor AlecJeffreys, a British scientist,
discovered a test that madeit possible to identify
an individual's DNA profile.
Jeffreys' breakthrough technique was first
used in a criminal case in .
But plant DNA had never beenused in a criminal case,
and scientists weren't evensure they could figure out a way
to extract DNA from the palo verde seed pods.
-Well, we certainly use fingerprinting a lot
in agriculture, but we've never looked
at this particular species of this tree.
Nobody has probably ever donemuch biology on it at all.
NARRATOR: Prosecutors hadcircumstantial evidence linking
Mark Bogan to the Denise Johnson's m*rder,
but they needed somethingmore definitive.
They knew they would haveto prove that Bogan was
at the crime scene, and the palo verde
pods were their best chance.
The scientists had no ideathat their research would
be the cornerstone of a m*rder case.
The Arizona Sheriff's department wanted
to know if there was any wayscientists could match the two
seed pods found in the back ofMark Bogan's truck to the palo
verde tree next to where they discovered
Denise Johnson's body.
But there were thousands of paloverde trees in the Phoenix area
alone, and there had never been a DNA
test on this type of tree.
-We had to learn how to do theanalysis so that we could say
do trees look different fromeach other in this species?
Because what we wanted to know was not
was this a palo verde tree, but could I
match it to that specific tree.
NARRATOR: Dr. Helentjaris used what
is known as a randomly amplifiedpolymorphic DNA technique,
or RAPID.
This is a less common test than RFLP,
the one used in searches for human DNA.
-One of the great things about RAPIDs
is that you're able to know nothing
about an individual speciesor type of organism.
You don't have to have any priorknowledge about it-- all you
have to do is get DNA and the method works.
NARRATOR: The test beginsby removing the beans
from their hard outer shell or pod.
-Seeds have DNA both from themother tree and other trees
that would have pollinated it,so we need to get rid of those
and just use the pod material, which
will only have DNA from the mother tree.
NARRATOR: The shells areput into liquid nitrogen,
making them brittle and easierto grind into a fine powder.
A chemical solution is added, and the DNA
floats free, a stickybundle of complex molecules.
The sample amount of DNA from a seed pod
is too small for analysis, soscientists increase the sample
size by copying the DNA strand.
They use a technique called polymerase
chain reaction, or PCR.
The copying process takesplace in a DNA thermal cycler.
Within a few hours, this technique
multiplies the DNA millions of times.
The DNA is then placedinto various lanes of a gel
with a dye added, and then subjected
to an electrical field.
Under ultraviolet light, it's possible to see how
the electrical current drawsthe negatively charged fragments
through the gel to the positive end at the top.
The results resemble a barcode, the genetic fingerprint
of a palo verde tree.
These fingerprints enabled Helentjaris
to make an importantdiscovery-- the two pods found
in Mark Bogan's truck matched each other,
and they also matched the pods taken
from the tree at the crime scene--
the tree next to where DeniseJohnson's body was discovered.
Every other palo verdes tree tested
had a completely different DNA profile.
It was the result that investigators
and the district attorney had hoped for.
-It wasn't the criminal itself, but it
was a particular tree that we had to identify.
And, in fact, they had to match--
we had to match that up.
-He was able to take the original samples,
take a part of the samplesfrom the pickup truck,
determine that those two podscame from the very same tree.
Then he compared those withsamples from all trees
and matched it to a treethere at the crime scene,
not knowing that the tree had the scrape on it,
to which he matched it.
NARRATOR: But there were only trees in the initial test,
and then the prosecution felt that wasn't
a large enough sample.
They needed to show a potential judge and jury
that all of the palo verde trees in Arizona
had a different DNA profile.
So the district attorneysent Dr. Helentjaris pods
from different trees, askingher to prove that each had
a separate and distinct DNA profile.
And he tried to trick Helentjaris.
-I did not tell Dr. Helentjaristhat I had gone back out
to the scene and had a deputy take a sample
from the same tree which had the scrape on it.
NARRATOR: Doctor Helentjarisproved that each of the pods
had a different DNA profile, and he also
discovered the prosecution's trick.
-I called him and I was alittle concerned because,
uh, you know, well we could tellall these trees apart and so
forth, but we put the sample back in
and it looked like it matchedone of these supposedly random
trees that they'd gone out and done.
-So it's like a touchdownin the end zone.
I knew it.
I knew he had hit on it.
Out of other samples thathe had tested on one gel,
he hit and matched perfectly.
NARRATOR: Police arrested Mark Bogan
and charged him for themurder of Denise Johnson.
He entered a plea of not guilty, but the question
remained-- would this new DNA evidence
be admissible in court?
No one had ever introduced plant DNA as evidence
in a criminal trial anywhere.
-We held a preliminaryhearing before the judge only,
to review the scientificevidence to see whether or not
it was evidence that was generally accepted
in the scientific communityas both valid and reliable.
NARRATOR: For three days,without a jury on hand,
lawyers and scientists arguedwhether plant DNA should
be admitted into a criminaltrial for the first time ever.
-What all of the scientists agreed about
was that plant DNA, like humanDNA, was unique to each plant,
and if properly tested, coulddistinguish one palo verde
tree from another palo verde tree.
And there seemed to be no dispute about that.
NARRATOR: Judge Boltondenied the defense motion
to prohibit Dr. Helentjaris' testimony,
thereby allowing the DNA evidence
to be admitted at the trial.
In setting a precedent, JudgeBolton had made DNA history.
-We were the first criminal casein the country that used a DNA
comparison of plant materialto-- as a piece of evidence.
NARRATOR: Now, armed withthe potent w*apon of the DNA
fingerprint, theprosecution went to trial,
attempting to prove to a jury that Mark
Bogan m*rder*d Denise Johnson.
What happened to Denise Johnsonon the night of May , ?
The prosecution believed that mark Bogan
met Denise Johnson at a phone booth.
-Hi, how you doing?
NARRATOR: They spoke brieflyand Denise asked for a ride.
-Sure, why not? -Thanks.
NARRATOR: They drove to a deserted location
for what was going to be aconsensual sexual encounter.
-How would you like to have some real fun?
NARRATOR: Bogan askedDenise if she would agree
to some light bondage andtied her wrists and ankles
with some picture frame wire and shoelaces.
Some of Bogan's ex-girlfriendswould testify that he enjoyed
bondage, and anotherwitness told investigators
that she saw the same type ofwire in the cab of his truck
just a few days earlier.
-No.
No, stop it now.
NARRATOR: At some point, Denise Johnson
objected to what was happeningand asked Bogan to stop.
Johnson got out of the truck and tried
to run, with Bogan fast behind.
Quickly, the situation turned violent.
The two struggled in the open field.
Bogan lost the pager he carried on his waist,
which fell into the high grass.
Bogan strangled Johnson with her own T-shirt,
then he dragged her body undersome nearby bushes and left.
As Bogan drove away, histruck brushed against the palo
verde tree, leaving the abrasion.
Two seed pods dropped intothe back of his truck.
An eyewitness saw a white trucksimilar to the one Bogan owned
coming out of the roadleading from the crime scene,
going through a stop sign, and speeding
off in the direction of Phoenix.
The witness said it wasabout : in the morning.
Bpgam lived minutes from the area,
and his wife told police sheawoke as Mark returned home,
just after : in the morning.
Most of the evidence against Mark Bogan
was circumstantial-- the lostbeeper, the picture frame wire,
his interest in bondage, and thewitness who saw a white truck
in the vicinity of the crimescene the night of the m*rder.
But the most critical evidencein the case was the plant DNA.
-There wasn't a fingerprint,there wasn't a drop of blood,
there wasn't a hair, therewere none of those things
that anybody could say were partof the victim's body found--
must've been left by the victim on the defendant
or on the defendant's property, or vice versa.
-He had, uh, admitted to the detectives
that he'd washed his truck the next morning.
He got rid of all of the evidence in the truck,
except for two polo verde pods.
-They needed evidence thatplaced Mark at the scene,
because he did have a credible story.
-As a prosecutor, I had a mantle of evidence
that I wanted to place uponthe shoulders of the defendant.
The palo verde pods tookthe mantle by the drawstring
and wrapped it around his neck.
NARRATOR: Unable to challengeDr. Helentjaris' findings
themselves, the defense challenged the evidence,
implying the pods were plantedin the back of Mark's truck.
But investigators said theseed pods were found in Bogan's
truck before samples weretaken from the crime scene.
-If I was going to plant evidence,
I would plant something that--that I know that I could match
later on and--and probably be a little
bit more assured of a conviction.
NARRATOR: The jury found Mark Bogan
guilty of m*rder in the first degree.
He was sentenced to life in prison
without parole for at least years.
The appellate court upheld the verdict.
Mark Bogan continues to maintain his innocence,
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 a plant.
-It was something that hadn'tbeen done before, something
that was certainly verydifferent from the routine
things that we do every day as judges.
-But I love my daughter very much.
I love all my children.
But it's something we just have to go through.
It's done.
I don't know what in the world could have
tripped him off to hurt her like that.
I don't know.
But I hope one day we'll find out.
01x05 - Planted Evidence
Watch/Buy Amazon Merchandise
Documentary that reveals how forensic science is used to solve violent crimes, mysterious accidents, and outbreaks of illness.
Documentary that reveals how forensic science is used to solve violent crimes, mysterious accidents, and outbreaks of illness.