Planted Evidence | S1 E5 | Forensic Files | FULL EPISODE | Forensic Files

[Music] 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 [Music] [Music] when investigators from the sheriff's
department arrived at the crime scene they gathered every possible piece of evidence the victim was nuded 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 shoelaces and what looked like picture hanging wire nearby investigators found
a ringe some articles of clothing then they heard some evidence 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 [Music] place 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 she wasn't
a bad girl she some of her friends I think she got with the wrong friends I ain't going to say they made
her do these things now she hung around with people that like 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 trust it too much 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 Mama her friends cautioned her that her lifestyle was probably going to find her in a lot of
trouble someday and eventually it did 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 boken said she asked for a ride to the interstate why not thanks once inside the truck she made
some sexual advances they pulled off the road and had sensual sex in the cab of his
[Music] truck 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 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 after a brief scuffle he retre his wallet she got out and left on foot Lan said that was the last he saw
of her 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 things fers or
fingernails of the victim there should be some residue of either the skin cells and or maybe even blood under the
fingernails 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 asphixiation due to
strangulation blood test showed cocaine in her system however there were no signs of any type of sexual activity
there was no seen 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
Myster on the day after police discovered Denise Johnson's body homicide detective Charlie Norton was
assigned to the case I decided that it would help me as the investigator to go out and familiarize myself with the
scene where the body was found 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 Verde tree just a few feet from where the body was found I had parked my car on the pavement I noticed
that there was a a branch that was hanging over um 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 meanwhile investigators confiscated Mark Ban'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
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 poo Verde tree was it possible that Ban's truck brushed against the Palo Verde tree at
the crime scene 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 test Tes in could match the bean pods from Ban's truck to the tree with the abrasion at the crime
scene I suggested to Charley at the time I said you know I said it'd be a real good idea if we could find someone
somewhere as in the United States that is involved in DNA testing the plant life and I said what the hell have we
got to lose you know where are we going to go from here what's the number for ID
Norton started working the phones calling scientists all over the United States yeah got uh 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 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 as
relevant to people in May maybe a way that's not quite as obvious sometimes through agriculture could DNA really
showed 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 Jeff a British scientist discovered a test that
made it possible possible to identify an individual's DNA profile jeffy's 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 Verde
seed pods well we certainly use fingerprinting a lot in agriculture but we'd never looked at this particular
species uh this tree nobody has probably ever done in biology on it at all 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 Verde pods were their best chance the scientists had no idea that
their research would be the Cornerstone of a murder case the Arizona Sheriff Department
wanted to know if there was any way scientists could match the two seed pods found in the back of Mark Ban's truck to
the Palo Verde tree next to where they discovered Denise Johnson's body but there were thousands of Palo
Verde 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 this species because what we wanted to
know was not was this a palty tree but can I match it to that specific tree Dr Helen jarus used what is known as a
randomly Amplified polymorphic 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 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 the test begins by removing the beans from their hard outer shell or pod the 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 pot material which will only have DNA from the mother tree the shells are put into liquid nitrogen
making them brittle and easier to grind into a fine powder a chem 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 Dy 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 Pao Verde
tree these fingerprints enabled Helen Jaris to make an important Discovery the two pods found in Mark Ban'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 Verde 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 determined that those two pods came from
the very same tree then he compared those with all samples from all 12 Trees in 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 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
Helen jarus pods from 100 different trees asking him to prove that each had a separate and distinct DNA profile and
he tried to trick Helen Jaris I did not tell Dr Helen jarus 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 Dr Helen jarus 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 uh you know well 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 endzone I knew it I knew he had hit on it out of 20 other samples that he had tested on
one Gil he hit and matched perfectly 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 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 for 3 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 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 palty tree from another palver tree and there seemed to be no dispute about that judge
Bolton denied the defense motion to prohibit Dr Helen Jar'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 uh as a piece of evidence now armed with the
potent weapon of a DNA fingerprint the prosecution went to trial attempting to prove to a jury that Mark
ban murdered Denise Johnson what happened to Denise Johnson on the night of May 2nd
1992 the prosecution believed that Mark Bogan met Denise Johnson at a phone booth hi how you doing they spoke
briefly and Denise asked for a ride sure why not thanks [Music] they drove to a deserted location for
what was going to be a consensual sexual [Music] encounter how would you like to have
some real funan 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 Ban'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 at some point Denise Johnson objected to what was happening and asked Bogan to stop
Johnson got out of the truck and tried to run with 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 Verde tree leaving the abrasion two seat ODS
dropped into the back of his truck an eyewitness saw a white truck similar to the one Bogen own 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: 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 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 vice 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 Pala verti pods they needed evidence that placed Mark at the scene uh cuz 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 palti pods and took the mantle by the drawring and wrapped it around his neck unable to
challenge Dr Helen Jar'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 Ban'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 and probably be a little bit more uh assured of a conviction 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 appell at court upheld the verdict Mark Bogan continues to maintain
his innocence and the appeal process is continuing I'm trying to forget this case cuz I'm the only person on the
planet that lost to a plan it was something that hadn't been done before uh 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 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] a [Music]

Early one morning in a deserted area outside of Phoenix, a motorcyclist discovered the body of a young woman.

Brief Summary

The murder of Denise Johnson leads to a landmark trial using plant DNA evidence against Mark Bogan.

Key points

Discovery of Denise Johnson's Body. A motorcyclist finds the body of Denise Johnson, a young woman who had been murdered.
Mark Bogan's Interrogation. Investigators notice scratch marks on Mark Bogan's face during his interrogation.
DNA Testing of Plant Material. For the first time, plant DNA is used as evidence in a murder case.
Mark Bogan Found Guilty. Mark Bogan is convicted of first-degree murder and sentenced to life in prison.

Episode highlights

Episode quotes

I ain't going to say they made her do these things.

A friend discussing Denise's lifestyle.

2:40WatchMar 4, 2025

Tension

75/ 100High tension

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