Forensic Files - Season 1, Episode 5 - Planted Evidence - Full Episode | Forensic Files

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

Early one morning in a deserted area outside of Phoenix, a motorcyclist discovered the body of a young woman. She had been beaten, bound, strangled and possibly raped. The nearby plants would tell investigators more about the killer than any other single piece of evidence.

Forensic Files is the longest-running true crime series in television history. Evidence and interviews with experts help solve real crimes, disease outbreaks and accidents around the world.

Brief Summary

The murder of Denise Johnson led to the first use of plant DNA evidence in a criminal trial, resulting in Mark Bogan's conviction.

Key points

The Discovery of Denise Johnson. A motorcyclist finds the body of Denise Johnson, leading to a complex investigation.
DNA Evidence Breakthrough. For the first time, plant DNA is used as evidence in a murder trial.
Mark Bogan's Conviction. Mark Bogan is found guilty of Denise Johnson's murder, sentenced to life in prison.

Episode highlights

Episode quotes

She wasn't a bad girl.

Denise's mother reflects on her daughter's life choices.

2:34WatchMay 20, 2021

Tension

75/ 100High tension

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