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[Music]
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early one morning in a deserted area
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outside of Phoenix a motorcyclist
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discovered the body of a young woman she
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had been beaten bound strangled and
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possibly
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raped the surrounding plants would tell
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more about her killer than any other
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single piece of evidence
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[Music]
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[Music]
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when investigators from the sheriff's
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department arrived at the crime scene
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they gathered every possible piece of
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evidence the victim was nuded except for
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a pulled up tank top and a t-shirt
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wrapped around her neck which was
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probably used to strangle her her wrists
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and ankles were Loosely bound with
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shoelaces and what looked like picture
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hanging wire nearby investigators found
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a ringe some articles of clothing then
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they heard some
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evidence it was a pager found deep in
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the grass a few feet from the
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body the discovery of the pager
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triggered a larger search and the
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photographer took some aerial
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photographs there appeared to be a
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circular area of matted grass where an
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altercation possibly took
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[Music]
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place police took the victim's remains
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to the medical examiner for
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identification and
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autopsy a fingerprint search identified
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the victim as 30-year-old Denise Johnson
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a single mother of two young children
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she was born and raised in an area of
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Phoenix known as the projects she wasn't
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a bad girl she some of her friends I
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think she got with the wrong
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friends I ain't going to say they made
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her do these things
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now she hung around with people that
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like to party drink and I don't really
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know what they were doing but she you
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know she was out there in the world with
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people that did drugs I'm sure and
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sometimes I think she trust it too much
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Denise made her living on the streets of
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Phoenix she had a history of short
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changing truck drivers in various drug
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deals at local truck stops which earned
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her the nickname twist Mama her friends
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cautioned her that her lifestyle was
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probably going to find her in a lot of
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trouble someday and eventually it did
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but who ended Denise Johnson's life the
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investigation began with the pager found
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lying near the body
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it belonged to this man a local trucker
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named Mark
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Bogan he said that on his way home from
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work the night before he stopped to make
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a phone call that's when he met Denise
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Johnson for the first time hi how you
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doing hello there boken said she asked
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for a ride to the interstate why not
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thanks once inside the truck she made
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some sexual advances they pulled off the
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road and had sensual sex in the cab of
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his
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[Music]
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truck afterwards as he was dropping her
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off he said she attempted to steal some
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of his things off the dashboard oh I had
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a really good time so did I baby did you
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oh always when I'm in the company of a
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lovely
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lady I would really love to have my
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wallet back after a brief scuffle he
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retre his wallet she got out and left on
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foot Lan said that was the last he saw
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of
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her the next morning he noticed his
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pager was missing assumed he had lost it
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and called the pager company to report
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it
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missing during the interrogation of Mark
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Bogan investigators noticed scratch
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marks on the side of his face if there
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were scratches on the suspect's face
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then you would expect that if those were
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in fact inflicted by things fers or
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fingernails of the victim there should
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be some residue of either the skin cells
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and or maybe even blood under the
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fingernails the autopsy of Denise
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Johnson revealed no skin or blood under
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any of her
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fingernails the medical examiner found
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that Denise Johnson's death was caused
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by asphixiation due to
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strangulation blood test showed cocaine
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in her system however there were no
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signs of any type of sexual activity
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there was no seen found no foreign hair
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clothing fibers or saliva found anywhere
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on her body the autopsy told
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investigators how Denise Johnson died
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but provided no clues about her killer
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their one suspect Mark Bogan was
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apparently a dead end the Sheriff's
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Office had not only a murder but a
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Myster on the day after police
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discovered Denise Johnson's body
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homicide detective Charlie Norton was
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assigned to the case I decided that it
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would help me as the investigator to go
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out and familiarize myself with the
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scene where the body was found Denise
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Johnson's body was discovered in a
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remote part of Maricopa County about a
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half an hour away from Downtown
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Phoenix Charlie Norton was looking for
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anything out of place or unusual
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anything that might have been overlooked
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the day
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before then he saw it something peculiar
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on a Palo Verde tree just a few feet
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from where the body was found I had
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parked my car on the pavement I noticed
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that there was a a branch that was
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hanging over um and when I looked at
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that Branch I noticed that there was a
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fresh abrasion and I had no idea what it
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might mean but I took a picture of it
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then I took some beans off of that
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particular tree meanwhile investigators
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confiscated Mark Ban's truck to look for
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possible evidence linking him or his
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truck to the crime scene it was
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completely clean no fingerprints semen
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blood saliva hair or clothing fibers no
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evidence at all that Denise Johnson was
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even in the
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truck but when investigators and police
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photographers looked in the back of the
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truck they made an interesting discovery
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they found two bean pods from a poo
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Verde
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tree was it possible that Ban's truck
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brushed against the Palo Verde tree at
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the crime scene causing two bean pods to
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drop into the back of the truck the
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problem was Palo Verde trees are very
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common in Arizona there are tens of
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thousands of them in the Phoenix area
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alone but Charlie Norton's boss had an
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idea to see if DNA test Tes in could
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match the bean pods from Ban's truck to
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the tree with the abrasion at the crime
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scene I suggested to Charley at the time
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I said you know I said it'd be a real
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good idea if we could find someone
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somewhere as in the United States that
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is involved in DNA testing the plant
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life and I said what the hell have we
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got to lose you know where are we going
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to go from here what's the number for ID
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Norton started working the phones
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calling scientists all over the United
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States yeah got uh answers like it
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couldn't be done to maybe it could be
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done and that if it could be done that
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the cost would be prohibitive 15
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telephone calls later he found someone
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who offered some hope ironically just
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100 miles away at the University of
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Arizona in Tucson I saw that as sort of
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a public service thing that we could do
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that we'd show some of this science as
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relevant to people in May maybe a way
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that's not quite as obvious sometimes
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through agriculture could DNA really
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showed that one plant or tree was
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different from another even though they
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were the same species DNA is present in
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all cells of all living things it's a
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little like a computer program
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containing all of the information
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necessary to create a living thing all
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humans have different DNA profiles
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except for identical
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twins in the early 1980s Dr Alec Jeff a
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British scientist discovered a test that
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made it possible possible to identify an
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individual's DNA profile jeffy's
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breakthrough technique was first used in
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a criminal case in
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1986 but plant DNA had never been used
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in a criminal case And scientists
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weren't even sure they could figure out
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a way to extract DNA from the Palo Verde
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seed pods well we certainly use
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fingerprinting a lot in agriculture but
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we'd never looked at this particular
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species uh this tree nobody has probably
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ever done in biology on it at all
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prosecutors had circumstantial evidence
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linking Mark Bogan to Denise Johnson's
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murder but they needed something more
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definitive they knew they would have to
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prove that Bogan was at the crime scene
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and the Palo Verde pods were their best
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chance the scientists had no idea that
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their research would be the Cornerstone
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of a murder
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case the Arizona Sheriff Department
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wanted to know if there was any way
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scientists could match the two seed pods
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found in the back of Mark Ban's truck to
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the Palo Verde tree next to where they
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discovered Denise Johnson's
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body but there were thousands of Palo
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Verde trees in the Phoenix area alone
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and there had never been a DNA test on
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this type of tree we had to learn how to
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do the analysis so that we could say do
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trees look different from each other in
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this species because what we wanted to
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know was not was this a palty tree but
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can I match it to that specific tree Dr
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Helen jarus used what is known as a
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randomly Amplified polymorphic DNA
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technique or rapid this is a less common
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test than rflp the one used in searches
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for human
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DNA one of the great things about Rapids
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is is that you're able to know nothing
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about an individual species or type of
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organism you don't have to have any
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prior knowledge about it all you have to
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do is get DNA and the method works the
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test begins by removing the beans from
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their hard outer shell or pod the seeds
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have DNA both from the mother tree and
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other trees that would have pollinated
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it so we need to get rid of those and
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just use the pot material which will
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only have DNA from the mother tree the
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shells are put into liquid nitrogen
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making them brittle and easier to grind
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into a fine
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powder a chem chemical solution is added
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and the DNA floats free a sticky bundle
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of complex
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molecules the sample amount of DNA from
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a seed pod is too small for analysis so
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scientists increase the sample size by
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copying the DNA strand they use a
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technique called polymerase Chain
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Reaction or
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PCR the copying process takes place in a
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DNA thermal cycler within a few hours
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this technique multiplies the DNA
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millions of times the DNA is then placed
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into various Lanes of a gel with a Dy
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added and then subjected to an
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electrical
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field under ultraviolet light it's
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possible to see how the electrical
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current draws the negatively charged
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fragments through the gel to the
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positive end at the
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top the results resemble a bar code the
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genetic fingerprint of a Pao Verde
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tree these fingerprints enabled Helen
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Jaris to make an important Discovery the
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two pods found in Mark Ban's truck
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matched each other and they also matched
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the pods taken from the tree at the
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crime scene the tree next to where
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Denise Johnson's body was discovered
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every other Palo Verde tree tested had a
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completely different DNA profile it was
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the result that investigators and the
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district attorney had hoped for it
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wasn't the criminal itself but it was a
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particular tree that we had to identify
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and in fact they had matched we had
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matched that up he was able
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to take the original samples take a part
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of the samples from the pickup truck
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determined that those two pods came from
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the very same tree then he compared
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those with all samples from all 12 Trees
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in matched it to a tree there at the
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crime scene not knowing that the tree
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had the scrape on it to which he matched
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it but there were only 12 Trees in the
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initial test and the prosecution felt
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that wasn't a large enough sample they
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needed to show a potential judge and
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jury that all of the Palo Verde trees in
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Arizona had a different DNA
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profile so the district attorney sent
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Helen jarus pods from 100 different
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trees asking him to prove that each had
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a separate and distinct DNA profile and
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he tried to trick Helen Jaris I did not
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tell Dr Helen jarus that I had gone back
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out to the scene had a deputy take a
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sample from the same tree which had the
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scrape on it Dr Helen jarus proved that
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each of the pods had a different DNA
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profile and he also discovered the
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prosecution's trick I called him and I
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was a little concerned because uh you
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know well we could tell all these trees
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apart and so forth but we put the sample
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back in and it looked like it matched
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one of these supposedly random trees
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that they'd gone out and done it's
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almost like a touchdown in the endzone I
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knew it I knew he had hit on it out of
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20 other samples that he had tested on
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one Gil he hit and matched perfectly
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police arrested Mark Bogan and charged
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him for the murder of Denise Johnson he
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entered a plea of not guilty but the
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question remained would this new DNA
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evidence be admissible in court no one
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had ever introduced plant DNA as
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evidence in a criminal trial anywhere we
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held a preliminary hearing before the
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judge only to review the scientific
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evidence to see whether or not it was
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evidence that was generally accepted in
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the scientific Community as both valid
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and reliable for 3 days without a jury
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on hand lawyers and scientists argued
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whether plant DNA should be admitted
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into a criminal trial for the first time
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ever what all of the scientists agreed
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about was that plant DNA like human DNA
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was unique to each plant and if properly
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tested could distinguish one palty tree
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from another palver tree and there
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seemed to be no dispute about that judge
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Bolton denied the defense motion to
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prohibit Dr Helen Jar's testimony
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thereby allowing the DNA evidence to be
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admitted at the trial in setting a
00:16:37
precedent judge Bolton had made DNA
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history we were the first criminal case
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in the country that used a DNA
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comparison of plant material to uh as a
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piece of evidence now armed with the
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potent weapon of a DNA fingerprint the
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prosecution went to trial
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attempting to prove to a jury that Mark
00:17:02
ban murdered Denise
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Johnson what happened to Denise Johnson
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on the night of May 2nd
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1992 the prosecution believed that Mark
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Bogan met Denise Johnson at a phone
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booth hi how you doing they spoke
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briefly and Denise asked for a ride sure
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why not thanks
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[Music]
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they drove to a deserted location for
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what was going to be a consensual sexual
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[Music]
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encounter how would you like to have
00:17:51
some real funan asked Denise if she
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would agree to some light bondage and
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tied her wrists and ankles with some
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picture frame wire and
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shoelaces some of Ban's ex-girlfriends
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would testify that he enjoyed bondage
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and another witness told investigators
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that she saw the same type of wire in
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the cab of his truck just a few days
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earlier no no stop it at some point
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Denise Johnson objected to what was
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happening and asked Bogan to stop
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Johnson got out of the truck and tried
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to run with fast behind quickly the
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situation turned violent the two
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struggled in the open field Bogan lost
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the pager he carried on his waist which
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fell into the high grass Bogan strangled
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Johnson with her own t-shirt then he
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dragged her body under some nearby
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bushes and
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left as Bogan drove away his truck
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brushed against a Palo Verde tree
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leaving the abrasion two seat ODS
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dropped into the back of his
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truck an eyewitness saw a white truck
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similar to the one Bogen own coming out
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of the road leading from the crime scene
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going through a stop sign and speeding
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off in the direction of Phoenix the
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witness said it was about 1:30 in the
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morning Bogan lived 18 minutes from the
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area and his wife told police she awoke
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as Mark returned home just after 2: in
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the morning most of the evidence against
00:19:30
Mark Bogan was circumstantial the Lost
00:19:33
beeper the picture frame wire his
00:19:36
interest in bondage and the witness who
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saw a white truck in the vicinity of the
00:19:41
crime scene the night of the murder but
00:19:45
the most critical evidence in the case
00:19:48
was the plant DNA there wasn't a
00:19:50
fingerprint there wasn't a drop of blood
00:19:53
there wasn't a hair there were none of
00:19:55
those things that anybody could say were
00:19:58
part of the victim's body found must
00:20:01
have been left by the victim on the
00:20:04
defendant or on the defendant's property
00:20:07
or vice versa he had admitted to the
00:20:09
detectives that he'd washed his truck
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the next morning he got rid of all of
00:20:13
the evidence in the truck except for two
00:20:15
Pala verti pods they needed evidence
00:20:18
that placed Mark at the scene uh cuz he
00:20:21
did have a credible story as a
00:20:22
prosecutor I had a mantle of evidence
00:20:24
that I wanted to place upon the
00:20:26
shoulders of the defendant the palti
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pods and took the mantle by the drawring
00:20:34
and wrapped it around his neck unable to
00:20:37
challenge Dr Helen Jar's findings
00:20:40
themselves the defense challenged the
00:20:42
evidence implying the pods were planted
00:20:45
in the back of Mark's truck but
00:20:47
investigators said the seed pods were
00:20:49
found in Ban's truck before samples were
00:20:52
taken from the crime scene if I was
00:20:55
going to plant evidence I would plant
00:20:56
something that that I
00:20:59
know that I could match later on and and
00:21:03
probably be a little bit
00:21:05
more uh assured of a conviction the jury
00:21:10
found Mark Bogan guilty of murder in the
00:21:13
first degree he was sentenced to life in
00:21:17
prison without parole for at least 25
00:21:20
years the appell at court upheld the
00:21:23
verdict Mark Bogan continues to maintain
00:21:26
his innocence and the appeal process is
00:21:29
continuing I'm trying to forget this
00:21:31
case cuz I'm the only person on the
00:21:33
planet that lost to a
00:21:34
plan it was something that hadn't been
00:21:37
done before uh something that was
00:21:42
certainly very different from the
00:21:45
routine things that we do every day as
00:21:47
judges but I love my daughter very much
00:21:50
I love all my
00:21:51
children but it's something we just have
00:21:55
to go through it's done I don't know
00:21:58
what in the world that could have
00:22:01
tripped him off to to hurt her like that
00:22:04
I don't know but I hope one day we'll
00:22:07
find out
00:22:11
[Music]
00:22:28
a
00:22:31
[Music]
